diff --git a/tests/nexus/CMakeLists.txt b/tests/nexus/CMakeLists.txt
index 30b387289..c38a25616 100644
--- a/tests/nexus/CMakeLists.txt
+++ b/tests/nexus/CMakeLists.txt
@@ -156,6 +156,7 @@ ot_nexus_test(5_5_4_2 "cert;nexus")
 ot_nexus_test(5_5_5 "cert;nexus")
 ot_nexus_test(5_5_7 "cert;nexus")
 ot_nexus_test(5_7_1 "cert;nexus")
+ot_nexus_test(5_7_2 "cert;nexus")
 ot_nexus_test(5_8_2 "cert;nexus")
 ot_nexus_test(5_8_3 "cert;nexus")
 ot_nexus_test(6_1_1 "cert;nexus")
diff --git a/tests/nexus/run_nexus_tests.sh b/tests/nexus/run_nexus_tests.sh
index 7b451e370..68777f330 100755
--- a/tests/nexus/run_nexus_tests.sh
+++ b/tests/nexus/run_nexus_tests.sh
@@ -86,6 +86,7 @@ DEFAULT_TESTS=(
     "5_5_5"
     "5_5_7"
     "5_7_1"
+    "5_7_2"
     "5_8_2"
     "5_8_3"
     "6_1_1_A"
diff --git a/tests/nexus/test_5_7_2.cpp b/tests/nexus/test_5_7_2.cpp
new file mode 100644
index 000000000..f5314b29e
--- /dev/null
+++ b/tests/nexus/test_5_7_2.cpp
@@ -0,0 +1,377 @@
+/*
+ *  Copyright (c) 2026, The OpenThread Authors.
+ *  All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *  1. Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *  3. Neither the name of the copyright holder nor the
+ *     names of its contributors may be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *  POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+
+#include "platform/nexus_core.hpp"
+#include "platform/nexus_node.hpp"
+#include "thread/network_diagnostic.hpp"
+
+namespace ot {
+namespace Nexus {
+
+/**
+ * Time to advance for a node to form a network and become leader, in milliseconds.
+ */
+static constexpr uint32_t kFormNetworkTime = 13 * 1000;
+
+/**
+ * Time to advance for a node to join as a child and upgrade to a router, in milliseconds.
+ */
+static constexpr uint32_t kAttachToRouterTime = 200 * 1000;
+
+/**
+ * Time to advance for the network to stabilize after nodes have attached.
+ */
+static constexpr uint32_t kStabilizationTime = 10 * 1000;
+
+/**
+ * Time to advance for the diagnostic response to be received.
+ */
+static constexpr uint32_t kDiagResponseTime = 5 * 1000;
+
+/**
+ * Time to wait for DIAG_GET to complete (20 seconds).
+ */
+static constexpr uint32_t kWait20Seconds = 20 * 1000;
+
+/**
+ * Time to wait before next step (2 seconds).
+ */
+static constexpr uint32_t kWait2Seconds = 2 * 1000;
+
+/**
+ * Number of routers in the topology.
+ */
+static constexpr uint8_t kNumRouters = 15;
+
+/**
+ * Base diagnostic TLV types used in Steps 2 and 8.
+ */
+static constexpr uint8_t kBaseDiagGetTlvs[] = {
+    NetworkDiagnostic::Tlv::kExtMacAddress, NetworkDiagnostic::Tlv::kAddress16,
+    NetworkDiagnostic::Tlv::kMode,          NetworkDiagnostic::Tlv::kConnectivity,
+    NetworkDiagnostic::Tlv::kRoute,         NetworkDiagnostic::Tlv::kLeaderData,
+    NetworkDiagnostic::Tlv::kNetworkData,   NetworkDiagnostic::Tlv::kIp6AddressList,
+    NetworkDiagnostic::Tlv::kChannelPages,
+};
+
+/**
+ * MAC Counters diagnostic TLV type used in Steps 3, 6, and 7.
+ */
+static constexpr uint8_t kMacCountersTlv[] = {NetworkDiagnostic::Tlv::kMacCounters};
+
+void Test5_7_2(void)
+{
+    /**
+     * 5.7.2 CoAP Diagnostic Get Query and Answer Commands – REED
+     *
+     * 5.7.2.1 Topology
+     * - Leader
+     * - Router_1
+     * - REED_1 (DUT)
+     * - (Additional routers as needed to satisfy REED conditions, typically a total of 16 active routers)
+     *
+     * 5.7.2.2 Purpose & Description
+     * This test case exercises the Diagnostic Get Query and Answer commands as part of the Network Management. This
+     *   test case topology is specific to REED DUTs.
+     *
+     * Spec Reference   | V1.1 Section | V1.3.0 Section
+     * -----------------|--------------|---------------
+     * Diag Commands    | 10.11.2      | 10.11.2
+     */
+
+    Core nexus;
+
+    Node &leader = nexus.CreateNode();
+    Node &reed1  = nexus.CreateNode();
+    Node *routers[kNumRouters];
+
+    leader.SetName("LEADER");
+    reed1.SetName("REED_1");
+
+    for (uint8_t i = 0; i < kNumRouters; i++)
+    {
+        routers[i] = &nexus.CreateNode();
+        routers[i]->SetName("ROUTER", i + 1);
+    }
+
+    nexus.AdvanceTime(0);
+
+    Instance::SetLogLevel(kLogLevelNote);
+
+    Log("---------------------------------------------------------------------------------------");
+    Log("Step 1: All");
+
+    /**
+     * Step 1: All
+     * - Description: Ensure topology is formed correctly.
+     * - Pass Criteria: N/A
+     */
+
+    /** Use AllowList to specify links between nodes. */
+    for (uint8_t i = 0; i < kNumRouters; i++)
+    {
+        leader.AllowList(*routers[i]);
+        routers[i]->AllowList(leader);
+    }
+
+    reed1.AllowList(*routers[0]);
+    routers[0]->AllowList(reed1);
+
+    leader.Form();
+    nexus.AdvanceTime(kFormNetworkTime);
+
+    for (uint8_t i = 0; i < kNumRouters; i++)
+    {
+        routers[i]->Join(leader);
+    }
+
+    nexus.AdvanceTime(kAttachToRouterTime);
+
+    for (uint8_t i = 0; i < kNumRouters; i++)
+    {
+        VerifyOrQuit(routers[i]->Get<Mle::Mle>().IsRouter());
+    }
+
+    reed1.Join(*routers[0], Node::kAsFtd);
+    nexus.AdvanceTime(kAttachToRouterTime);
+    nexus.AdvanceTime(kStabilizationTime);
+
+    VerifyOrQuit(reed1.Get<Mle::Mle>().IsChild());
+
+    const Ip6::Address &reedRloc = reed1.Get<Mle::Mle>().GetMeshLocalRloc();
+
+    Log("---------------------------------------------------------------------------------------");
+    Log("Step 2: Leader");
+
+    /**
+     * Step 2: Leader
+     * - Description: Harness instructs the device to send DIAG_GET.req to the DUT’s Routing Locator (RLOC) for the
+     *   following diagnostic TLV types:
+     *   - TLV Type 0 – MAC Extended Address (64-bit)
+     *   - TLV Type 1 - MAC Address (16-bit)
+     *   - TLV Type 2 - Mode (Capability information)
+     *   - TLV Type 4 – Connectivity
+     *   - TLV Type 5 – Route64
+     *   - TLV Type 6 – Leader Data
+     *   - TLV Type 7 – Network Data
+     *   - TLV Type 8 – IPv6 address list
+     *   - TLV Type 17 – Channel Pages
+     * - Pass Criteria:
+     *   - The DUT MUST respond with a DIAG_GET.rsp response containing the requested diagnostic TLVs:
+     *   - CoAP Response Code: 2.04 Changed
+     *   - CoAP Payload:
+     *     - TLV Type 0 - MAC Extended Address (64-bit)
+     *     - TLV Type 1 - MAC Address (16-bit)
+     *     - TLV Type 2 - Mode (Capability information)
+     *     - TLV Type 4 – Connectivity
+     *     - TLV Type 5 – Route64 (optional)
+     *     - TLV Type 6 – Leader Data
+     *     - TLV Type 7 – Network Data
+     *     - TLV Type 8 – IPv6 address list
+     *     - TLV Type 17 – Channel Pages
+     *   - The presence of each TLV MUST be validated. Where possible, the value of the TLVs MUST be validated.
+     */
+
+    SuccessOrQuit(leader.Get<NetworkDiagnostic::Client>().SendDiagnosticGet(
+        reedRloc, kBaseDiagGetTlvs, sizeof(kBaseDiagGetTlvs), nullptr, nullptr));
+    nexus.AdvanceTime(kDiagResponseTime);
+
+    Log("---------------------------------------------------------------------------------------");
+    Log("Step 3: Leader");
+
+    /**
+     * Step 3: Leader
+     * - Description: Harness instructs the device to send DIAG_GET.req to the DUT’s Routing Locator (RLOC) for the
+     *   following diagnostic TLV type:
+     *   - TLV Type 9 - MAC Counters
+     * - Pass Criteria:
+     *   - The DUT MUST respond with a DIAG_GET.rsp response containing the requested diagnostic TLV:
+     *   - CoAP Response Code: 2.04 Changed
+     *   - CoAP Payload:
+     *     - TLV Type 9 - MAC Counters
+     *   - TLV Type 9 - MAC Counters MUST contain a list of MAC Counters.
+     */
+
+    SuccessOrQuit(leader.Get<NetworkDiagnostic::Client>().SendDiagnosticGet(reedRloc, kMacCountersTlv,
+                                                                            sizeof(kMacCountersTlv), nullptr, nullptr));
+    nexus.AdvanceTime(kDiagResponseTime);
+
+    Log("---------------------------------------------------------------------------------------");
+    Log("Step 4: Leader");
+
+    /**
+     * Step 4: Leader
+     * - Description: Harness instructs the device to send DIAG_GET.req to the DUT’s Routing Locator (RLOC) for the
+     *   following diagnostic TLV types:
+     *   - TLV Type 3 – Timeout
+     *   - TLV Type 16 – Child Table TLV
+     * - Pass Criteria:
+     *   - The DUT MUST respond with a DIAG_GET.rsp response containing the required diagnostic TLV payload:
+     *   - CoAP Response Code: 2.04 Changed
+     *   - CoAP Payload:
+     *     - The Timeout TLV MUST NOT be present.
+     */
+
+    uint8_t tlvTypes4[] = {NetworkDiagnostic::Tlv::kTimeout, NetworkDiagnostic::Tlv::kChildTable};
+
+    SuccessOrQuit(leader.Get<NetworkDiagnostic::Client>().SendDiagnosticGet(reedRloc, tlvTypes4, sizeof(tlvTypes4),
+                                                                            nullptr, nullptr));
+    nexus.AdvanceTime(kDiagResponseTime);
+
+    Log("---------------------------------------------------------------------------------------");
+    Log("Step 5: Leader");
+
+    /**
+     * Step 5: Leader
+     * - Description: Harness instructs the device to send DIAG_GET.req to the DUT’s Routing Locator (RLOC) for the
+     *   following diagnostic TLV types:
+     *   - TLV Type 14 – Battery Level
+     *   - TLV Type 15 – Supply Voltage
+     * - Pass Criteria:
+     *   - The DUT MUST respond with a DIAG_GET.rsp response optionally containing the requested diagnostic TLVs:
+     *   - CoAP Response Code: 2.04 Changed
+     *   - CoAP Payload:
+     *     - TLV Type 14 – Battery Level (optional)
+     *     - TLV Type 15 – Supply Voltage (optional)
+     */
+
+    uint8_t tlvTypes5[] = {NetworkDiagnostic::Tlv::kBatteryLevel, NetworkDiagnostic::Tlv::kSupplyVoltage};
+
+    SuccessOrQuit(leader.Get<NetworkDiagnostic::Client>().SendDiagnosticGet(reedRloc, tlvTypes5, sizeof(tlvTypes5),
+                                                                            nullptr, nullptr));
+    nexus.AdvanceTime(kDiagResponseTime);
+
+    Log("---------------------------------------------------------------------------------------");
+    Log("Step 5a: Test Harness");
+
+    /**
+     * Step 5a: Test Harness
+     * - Description: Harness waits 20 seconds to allow DIAG_GET to complete.
+     * - Pass Criteria: N/A
+     */
+
+    nexus.AdvanceTime(kWait20Seconds);
+
+    Log("---------------------------------------------------------------------------------------");
+    Log("Step 6: Leader");
+
+    /**
+     * Step 6: Leader
+     * - Description: Harness instructs the device to send DIAG_RST.ntf to DUT’s Routing Locator (RLOC) for the
+     *   following diagnostic TLV type:
+     *   - TLV Type 9 - MAC Counters
+     * - Pass Criteria:
+     *   - The DUT MUST respond with a CoAP response:
+     *   - CoAP Response Code: 2.04 Changed
+     */
+
+    SuccessOrQuit(leader.Get<NetworkDiagnostic::Client>().SendDiagnosticReset(reedRloc, kMacCountersTlv,
+                                                                              sizeof(kMacCountersTlv)));
+    nexus.AdvanceTime(kDiagResponseTime);
+
+    Log("---------------------------------------------------------------------------------------");
+    Log("Step 6a: Test Harness");
+
+    /**
+     * Step 6a: Test Harness
+     * - Description: Harness waits ONLY 2 seconds before executing next step.
+     * - Pass Criteria: N/A
+     */
+
+    nexus.AdvanceTime(kWait2Seconds);
+
+    Log("---------------------------------------------------------------------------------------");
+    Log("Step 7: Leader");
+
+    /**
+     * Step 7: Leader
+     * - Description: Harness instructs the device to send DIAG_GET.req to the DUT’s Routing Locator (RLOC) for the
+     *   following diagnostic TLV type:
+     *   - TLV Type 9 - MAC Counters
+     * - Pass Criteria:
+     *   - The DUT MUST respond with a DIAG_GET.rsp response containing the requested diagnostic TLV:
+     *   - CoAP Response Code: 2.04 Changed
+     *   - CoAP Payload:
+     *     - TLV Type 9 - MAC Counters
+     *   - TLV Type 9 - MAC Counters MUST contain a list of MAC Counters with 0 value or less than value returned in
+     *     step 3.
+     */
+
+    SuccessOrQuit(leader.Get<NetworkDiagnostic::Client>().SendDiagnosticGet(reedRloc, kMacCountersTlv,
+                                                                            sizeof(kMacCountersTlv), nullptr, nullptr));
+    nexus.AdvanceTime(kDiagResponseTime);
+
+    Log("---------------------------------------------------------------------------------------");
+    Log("Step 8: Leader");
+
+    /**
+     * Step 8: Leader
+     * - Description: Harness instructs the device to send DIAG_GET.query to Realm-Local All-Nodes multicast address
+     *   (FF03::1) for the following diagnostic TLV types:
+     *   - TLV Type 0 – MAC Extended Address (64-bit)
+     *   - TLV Type 1 - MAC Address (16-bit)
+     *   - TLV Type 2 - Mode (Capability information)
+     *   - TLV Type 4 – Connectivity
+     *   - TLV Type 5 – Route64
+     *   - TLV Type 6 – Leader Data
+     *   - TLV Type 7 – Network Data
+     *   - TLV Type 8 – IPv6 address list
+     *   - TLV Type 17 – Channel Pages
+     * - Pass Criteria:
+     *   - The DUT MUST respond with a DIAG_GET.ans response containing the requested diagnostic TLVs:
+     *   - CoAP Payload:
+     *     - TLV Type 0 - MAC Extended Address (64-bit)
+     *     - TLV Type 1 - MAC Address (16-bit)
+     *     - TLV Type 2 - Mode (Capability information)
+     *     - TLV Type 4 – Connectivity
+     *     - TLV Type 5 – Route64 (optional)
+     *     - TLV Type 6 – Leader Data
+     *     - TLV Type 7 – Network Data
+     *     - TLV Type 8 – IPv6 address list
+     *     - TLV Type 17 – Channel Pages
+     *   - The presence of each TLV MUST be validated. Where possible, the value of the TLVs MUST be validated.
+     */
+
+    SuccessOrQuit(leader.Get<NetworkDiagnostic::Client>().SendDiagnosticGet(
+        Ip6::Address::GetRealmLocalAllNodesMulticast(), kBaseDiagGetTlvs, sizeof(kBaseDiagGetTlvs), nullptr, nullptr));
+    nexus.AdvanceTime(kDiagResponseTime);
+
+    nexus.SaveTestInfo("test_5_7_2.json");
+}
+
+} // namespace Nexus
+} // namespace ot
+
+int main(void)
+{
+    ot::Nexus::Test5_7_2();
+    printf("All tests passed\n");
+    return 0;
+}
diff --git a/tests/nexus/verify_5_7_2.py b/tests/nexus/verify_5_7_2.py
new file mode 100644
index 000000000..5601aa920
--- /dev/null
+++ b/tests/nexus/verify_5_7_2.py
@@ -0,0 +1,287 @@
+#!/usr/bin/env python3
+#
+#  Copyright (c) 2026, The OpenThread Authors.
+#  All rights reserved.
+#
+#  Redistribution and use in source and binary forms, with or without
+#  modification, are permitted provided that the following conditions are met:
+#  1. Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer.
+#  2. Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in the
+#     documentation and/or other materials provided with the distribution.
+#  3. Neither the name of the copyright holder nor the
+#     names of its contributors may be used to endorse or promote products
+#     derived from this software without specific prior written permission.
+#
+#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+#  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+#  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+#  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+#  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+#  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+#  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+#  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+#  POSSIBILITY OF SUCH DAMAGE.
+#
+
+import sys
+import os
+
+# Add the current directory to sys.path to find verify_utils
+CUR_DIR = os.path.dirname(os.path.abspath(__file__))
+sys.path.append(CUR_DIR)
+
+import verify_utils
+from pktverify import consts
+from pktverify.null_field import nullField
+
+
+def verify(pv):
+    # 5.7.2 CoAP Diagnostic Get Query and Answer Commands – REED
+    #
+    # 5.7.2.1 Topology
+    # - Leader
+    # - Router_1
+    # - REED_1 (DUT)
+    # - (Additional routers as needed to satisfy REED conditions, typically a total of 16 active routers)
+    #
+    # 5.7.2.2 Purpose & Description
+    # This test case exercises the Diagnostic Get Query and Answer commands as part of the Network Management. This
+    #   test case topology is specific to REED DUTs.
+    #
+    # Spec Reference   | V1.1 Section | V1.3.0 Section
+    # -----------------|--------------|---------------
+    # Diag Commands    | 10.11.2      | 10.11.2
+
+    EXPECTED_DIAG_GET_TLVS = {
+        consts.DG_MAC_EXTENDED_ADDRESS_TLV, consts.DG_MAC_ADDRESS_TLV, consts.DG_MODE_TLV, consts.DG_CONNECTIVITY_TLV,
+        consts.DG_LEADER_DATA_TLV, consts.DG_NETWORK_DATA_TLV, consts.DG_IPV6_ADDRESS_LIST_TLV,
+        consts.DG_CHANNEL_PAGES_TLV
+    }
+
+    pkts = pv.pkts
+    pv.summary.show()
+
+    LEADER = pv.vars['LEADER']
+    LEADER_RLOC = pv.vars['LEADER_RLOC']
+    REED_1 = pv.vars['REED_1']
+    REED_1_RLOC = pv.vars['REED_1_RLOC']
+
+    # Step 1: All
+    # - Description: Ensure topology is formed correctly.
+    # - Pass Criteria: N/A
+    print("Step 1: Ensure topology is formed correctly.")
+
+    # Step 2: Leader
+    # - Description: Harness instructs the device to send DIAG_GET.req to the DUT’s Routing Locator (RLOC) for the
+    #   following diagnostic TLV types:
+    #   - TLV Type 0 – MAC Extended Address (64-bit)
+    #   - TLV Type 1 - MAC Address (16-bit)
+    #   - TLV Type 2 - Mode (Capability information)
+    #   - TLV Type 4 – Connectivity
+    #   - TLV Type 5 – Route64
+    #   - TLV Type 6 – Leader Data
+    #   - TLV Type 7 – Network Data
+    #   - TLV Type 8 – IPv6 address list
+    #   - TLV Type 17 – Channel Pages
+    # - Pass Criteria:
+    #   - The DUT MUST respond with a DIAG_GET.rsp response containing the requested diagnostic TLVs:
+    #   - CoAP Response Code: 2.04 Changed
+    #   - CoAP Payload:
+    #     - TLV Type 0 - MAC Extended Address (64-bit)
+    #     - TLV Type 1 - MAC Address (16-bit)
+    #     - TLV Type 2 - Mode (Capability information)
+    #     - TLV Type 4 – Connectivity
+    #     - TLV Type 5 – Route64 (optional)
+    #     - TLV Type 6 – Leader Data
+    #     - TLV Type 7 – Network Data
+    #     - TLV Type 8 – IPv6 address list
+    #     - TLV Type 17 – Channel Pages
+    #   - The presence of each TLV MUST be validated. Where possible, the value of the TLVs MUST be validated.
+    print("Step 2: Leader sends DIAG_GET.req to REED_1.")
+    pkts.filter_ipv6_src(LEADER_RLOC).\
+        filter_ipv6_dst(REED_1_RLOC).\
+        filter_coap_request(consts.DIAG_GET_URI).\
+        filter(lambda p: consts.DG_TYPE_LIST_TLV in p.coap.tlv.type).\
+        must_next()
+
+    pkts.filter_ipv6_src(REED_1_RLOC).\
+        filter_ipv6_dst(LEADER_RLOC).\
+        filter_coap_ack(consts.DIAG_GET_URI).\
+        filter(lambda p: EXPECTED_DIAG_GET_TLVS <= set(p.coap.tlv.type)).\
+        must_next()
+
+    # Step 3: Leader
+    # - Description: Harness instructs the device to send DIAG_GET.req to the DUT’s Routing Locator (RLOC) for the
+    #   following diagnostic TLV type:
+    #   - TLV Type 9 - MAC Counters
+    # - Pass Criteria:
+    #   - The DUT MUST respond with a DIAG_GET.rsp response containing the requested diagnostic TLV:
+    #   - CoAP Response Code: 2.04 Changed
+    #   - CoAP Payload:
+    #     - TLV Type 9 - MAC Counters
+    #   - TLV Type 9 - MAC Counters MUST contain a list of MAC Counters.
+    print("Step 3: Leader sends DIAG_GET.req for MAC Counters.")
+    pkts.filter_ipv6_src(LEADER_RLOC).\
+        filter_ipv6_dst(REED_1_RLOC).\
+        filter_coap_request(consts.DIAG_GET_URI).\
+        filter(lambda p: consts.DG_TYPE_LIST_TLV in p.coap.tlv.type).\
+        must_next()
+
+    p3 = pkts.filter_ipv6_src(REED_1_RLOC).\
+        filter_ipv6_dst(LEADER_RLOC).\
+        filter_coap_ack(consts.DIAG_GET_URI).\
+        filter(lambda p: consts.DG_MAC_COUNTERS_TLV in p.coap.tlv.type).\
+        must_next()
+
+    mac_counters_step_3 = [int(val) for val in p3.coap.tlv.mac_counter]
+
+    # Step 4: Leader
+    # - Description: Harness instructs the device to send DIAG_GET.req to the DUT’s Routing Locator (RLOC) for the
+    #   following diagnostic TLV types:
+    #   - TLV Type 3 – Timeout
+    #   - TLV Type 16 – Child Table TLV
+    # - Pass Criteria:
+    #   - The DUT MUST respond with a DIAG_GET.rsp response containing the required diagnostic TLV payload:
+    #   - CoAP Response Code: 2.04 Changed
+    #   - CoAP Payload:
+    #     - The Timeout TLV MUST NOT be present.
+    print("Step 4: Leader sends DIAG_GET.req for Timeout and Child Table.")
+    pkts.filter_ipv6_src(LEADER_RLOC).\
+        filter_ipv6_dst(REED_1_RLOC).\
+        filter_coap_request(consts.DIAG_GET_URI).\
+        filter(lambda p: consts.DG_TYPE_LIST_TLV in p.coap.tlv.type).\
+        must_next()
+
+    pkts.filter_ipv6_src(REED_1_RLOC).\
+        filter_ipv6_dst(LEADER_RLOC).\
+        filter_coap_ack(consts.DIAG_GET_URI).\
+        filter(lambda p: p.coap.tlv.type is nullField or \
+               consts.DG_TIMEOUT_TLV not in p.coap.tlv.type).\
+        must_next()
+
+    # Step 5: Leader
+    # - Description: Harness instructs the device to send DIAG_GET.req to the DUT’s Routing Locator (RLOC) for the
+    #   following diagnostic TLV types:
+    #   - TLV Type 14 – Battery Level
+    #   - TLV Type 15 – Supply Voltage
+    # - Pass Criteria:
+    #   - The DUT MUST respond with a DIAG_GET.rsp response optionally containing the requested diagnostic TLVs:
+    #   - CoAP Response Code: 2.04 Changed
+    #   - CoAP Payload:
+    #     - TLV Type 14 – Battery Level (optional)
+    #     - TLV Type 15 – Supply Voltage (optional)
+    print("Step 5: Leader sends DIAG_GET.req for Battery Level and Supply Voltage.")
+    pkts.filter_ipv6_src(LEADER_RLOC).\
+        filter_ipv6_dst(REED_1_RLOC).\
+        filter_coap_request(consts.DIAG_GET_URI).\
+        filter(lambda p: consts.DG_TYPE_LIST_TLV in p.coap.tlv.type).\
+        must_next()
+
+    pkts.filter_ipv6_src(REED_1_RLOC).\
+        filter_ipv6_dst(LEADER_RLOC).\
+        filter_coap_ack(consts.DIAG_GET_URI).\
+        must_next()
+
+    # Step 5a: Test Harness
+    # - Description: Harness waits 20 seconds to allow DIAG_GET to complete.
+    # - Pass Criteria: N/A
+    print("Step 5a: Harness waits 20 seconds.")
+
+    # Step 6: Leader
+    # - Description: Harness instructs the device to send DIAG_RST.ntf to DUT’s Routing Locator (RLOC) for the
+    #   following diagnostic TLV type:
+    #   - TLV Type 9 - MAC Counters
+    # - Pass Criteria:
+    #   - The DUT MUST respond with a CoAP response:
+    #   - CoAP Response Code: 2.04 Changed
+    print("Step 6: Leader sends DIAG_RST.ntf.")
+    pkts.filter_ipv6_src(LEADER_RLOC).\
+        filter_ipv6_dst(REED_1_RLOC).\
+        filter_coap_request(consts.DIAG_RST_URI).\
+        filter(lambda p: consts.DG_TYPE_LIST_TLV in p.coap.tlv.type).\
+        must_next()
+
+    pkts.filter_ipv6_src(REED_1_RLOC).\
+        filter_ipv6_dst(LEADER_RLOC).\
+        filter_coap_ack(consts.DIAG_RST_URI).\
+        must_next()
+
+    # Step 6a: Test Harness
+    # - Description: Harness waits ONLY 2 seconds before executing next step.
+    # - Pass Criteria: N/A
+    print("Step 6a: Harness waits 2 seconds.")
+
+    # Step 7: Leader
+    # - Description: Harness instructs the device to send DIAG_GET.req to the DUT’s Routing Locator (RLOC) for the
+    #   following diagnostic TLV type:
+    #   - TLV Type 9 - MAC Counters
+    # - Pass Criteria:
+    #   - The DUT MUST respond with a DIAG_GET.rsp response containing the requested diagnostic TLV:
+    #   - CoAP Response Code: 2.04 Changed
+    #   - CoAP Payload:
+    #     - TLV Type 9 - MAC Counters
+    #   - TLV Type 9 - MAC Counters MUST contain a list of MAC Counters with 0 value or less than value returned in
+    #     step 3.
+    print("Step 7: Leader sends DIAG_GET.req for MAC Counters after reset.")
+    pkts.filter_ipv6_src(LEADER_RLOC).\
+        filter_ipv6_dst(REED_1_RLOC).\
+        filter_coap_request(consts.DIAG_GET_URI).\
+        filter(lambda p: consts.DG_TYPE_LIST_TLV in p.coap.tlv.type).\
+        must_next()
+
+    p7 = pkts.filter_ipv6_src(REED_1_RLOC).\
+        filter_ipv6_dst(LEADER_RLOC).\
+        filter_coap_ack(consts.DIAG_GET_URI).\
+        filter(lambda p: consts.DG_MAC_COUNTERS_TLV in p.coap.tlv.type).\
+        must_next()
+
+    mac_counters_step_7 = [int(val) for val in p7.coap.tlv.mac_counter]
+    for i in range(len(mac_counters_step_3)):
+        assert mac_counters_step_7[i] <= mac_counters_step_3[i], \
+            f"MAC counter {i} increased after reset: {mac_counters_step_3[i]} -> {mac_counters_step_7[i]}"
+
+    # Step 8: Leader
+    # - Description: Harness instructs the device to send DIAG_GET.query to Realm-Local All-Nodes multicast address
+    #   (FF03::1) for the following diagnostic TLV types:
+    #   - TLV Type 0 – MAC Extended Address (64-bit)
+    #   - TLV Type 1 - MAC Address (16-bit)
+    #   - TLV Type 2 - Mode (Capability information)
+    #   - TLV Type 4 – Connectivity
+    #   - TLV Type 5 – Route64
+    #   - TLV Type 6 – Leader Data
+    #   - TLV Type 7 – Network Data
+    #   - TLV Type 8 – IPv6 address list
+    #   - TLV Type 17 – Channel Pages
+    # - Pass Criteria:
+    #   - The DUT MUST respond with a DIAG_GET.ans response containing the requested diagnostic TLVs:
+    #   - CoAP Payload:
+    #     - TLV Type 0 - MAC Extended Address (64-bit)
+    #     - TLV Type 1 - MAC Address (16-bit)
+    #     - TLV Type 2 - Mode (Capability information)
+    #     - TLV Type 4 – Connectivity
+    #     - TLV Type 5 – Route64 (optional)
+    #     - TLV Type 6 – Leader Data
+    #     - TLV Type 7 – Network Data
+    #     - TLV Type 8 – IPv6 address list
+    #     - TLV Type 17 – Channel Pages
+    #   - The presence of each TLV MUST be validated. Where possible, the value of the TLVs MUST be validated.
+    print("Step 8: Leader sends DIAG_GET.query to FF03::1.")
+    pkts.filter_ipv6_src(LEADER_RLOC).\
+        filter_ipv6_dst("ff03::1").\
+        filter_coap_request(consts.DIAG_GET_QRY_URI).\
+        filter(lambda p: consts.DG_TYPE_LIST_TLV in p.coap.tlv.type).\
+        must_next()
+
+    pkts.filter_ipv6_src(REED_1_RLOC).\
+        filter_ipv6_dst(LEADER_RLOC).\
+        filter_coap_request(consts.DIAG_GET_ANS_URI).\
+        filter(lambda p: EXPECTED_DIAG_GET_TLVS <= set(p.coap.tlv.type)).\
+        must_next()
+
+
+if __name__ == '__main__':
+    verify_utils.run_main(verify)