diff --git a/nimble/transport/syscfg.yml b/nimble/transport/syscfg.yml
index a4ae6d56f..becd81d61 100644
--- a/nimble/transport/syscfg.yml
+++ b/nimble/transport/syscfg.yml
@@ -57,7 +57,7 @@ syscfg.defs:
         value: 10
     BLE_TRANSPORT_ACL_SIZE:
         description: Size of each buffer in ACL pool.
-        value: 255
+        value: 251
     BLE_TRANSPORT_EVT_COUNT:
         description: >
             Number of event buffers available in transport.
diff --git a/tools/hci_throughput/targets/nordic_pca10040_blehci/syscfg.yml b/tools/hci_throughput/targets/nordic_pca10040_blehci/syscfg.yml
index 4de2fdd2c..1c2bbee27 100644
--- a/tools/hci_throughput/targets/nordic_pca10040_blehci/syscfg.yml
+++ b/tools/hci_throughput/targets/nordic_pca10040_blehci/syscfg.yml
@@ -24,5 +24,4 @@ syscfg.vals:
   MSYS_1_BLOCK_COUNT: 80
   MSYS_1_BLOCK_SIZE: 308
   BLE_TRANSPORT_ACL_COUNT: 80
-  BLE_TRANSPORT_ACL_SIZE: 255
 
diff --git a/tools/hci_throughput/targets/nordic_pca10056_blehci/syscfg.yml b/tools/hci_throughput/targets/nordic_pca10056_blehci/syscfg.yml
index 61f14a788..1c65d055b 100644
--- a/tools/hci_throughput/targets/nordic_pca10056_blehci/syscfg.yml
+++ b/tools/hci_throughput/targets/nordic_pca10056_blehci/syscfg.yml
@@ -29,4 +29,3 @@ syscfg.vals:
   MSYS_1_BLOCK_COUNT: 80
   MSYS_1_BLOCK_SIZE: 308
   BLE_TRANSPORT_ACL_COUNT: 80
-  BLE_TRANSPORT_ACL_SIZE: 255
\ No newline at end of file
diff --git a/tools/hci_throughput/targets/nordic_pca10059_blehci/syscfg.yml b/tools/hci_throughput/targets/nordic_pca10059_blehci/syscfg.yml
index f27e8c0b8..6fc26b9db 100644
--- a/tools/hci_throughput/targets/nordic_pca10059_blehci/syscfg.yml
+++ b/tools/hci_throughput/targets/nordic_pca10059_blehci/syscfg.yml
@@ -29,4 +29,3 @@ syscfg.vals:
   MSYS_1_BLOCK_COUNT: 80
   MSYS_1_BLOCK_SIZE: 308
   BLE_TRANSPORT_ACL_COUNT: 80
-  BLE_TRANSPORT_ACL_SIZE: 255
\ No newline at end of file
diff --git a/tools/hci_throughput/targets/nordic_pca10095_app_blehci/syscfg.yml b/tools/hci_throughput/targets/nordic_pca10095_app_blehci/syscfg.yml
index ad3399349..c7ff62bba 100644
--- a/tools/hci_throughput/targets/nordic_pca10095_app_blehci/syscfg.yml
+++ b/tools/hci_throughput/targets/nordic_pca10095_app_blehci/syscfg.yml
@@ -33,7 +33,6 @@ syscfg.vals:
     USBD_WINDOWS_COMP_ID: 1
 
     BLE_TRANSPORT_ACL_COUNT: 80
-    BLE_TRANSPORT_ACL_SIZE: 255
     MSYS_1_BLOCK_COUNT: 80
     MSYS_1_BLOCK_SIZE: 308
     IPC_NRF5340_BUF_SZ: 3072
diff --git a/tools/hci_throughput/targets/nordic_pca10095_net_blehci/syscfg.yml b/tools/hci_throughput/targets/nordic_pca10095_net_blehci/syscfg.yml
index a086199a6..7f0b5b60f 100644
--- a/tools/hci_throughput/targets/nordic_pca10095_net_blehci/syscfg.yml
+++ b/tools/hci_throughput/targets/nordic_pca10095_net_blehci/syscfg.yml
@@ -28,7 +28,6 @@ syscfg.vals:
     BLE_LL_HCI_VS_EVENT_ON_ASSERT: 1
 
     BLE_TRANSPORT_ACL_COUNT: 80
-    BLE_TRANSPORT_ACL_SIZE: 255
     MSYS_1_BLOCK_COUNT: 80
     MSYS_1_BLOCK_SIZE: 308
     IPC_NRF5340_BUF_SZ: 3072