diff --git a/tests/bluetooth/tester/boards/nrf52840dk_nrf52840.conf b/tests/bluetooth/tester/boards/nrf52840dk_nrf52840.conf
index 29139393b46..5bb1c4d8284 100644
--- a/tests/bluetooth/tester/boards/nrf52840dk_nrf52840.conf
+++ b/tests/bluetooth/tester/boards/nrf52840dk_nrf52840.conf
@@ -12,6 +12,7 @@ CONFIG_LOG_BUFFER_SIZE=4096
 CONFIG_RTT_CONSOLE=y
 CONFIG_LOG_BACKEND_RTT=y
 CONFIG_LOG_BACKEND_RTT_MODE_DROP=y
+CONFIG_LOG_BACKEND_RTT_MESSAGE_SIZE=256
 CONFIG_USE_SEGGER_RTT=y
 CONFIG_SEGGER_RTT_BUFFER_SIZE_UP=4096
 CONFIG_LOG_BACKEND_SHOW_COLOR=n
diff --git a/tests/bluetooth/tester/boards/nrf5340_audio_dk_nrf5340_cpuapp.conf b/tests/bluetooth/tester/boards/nrf5340_audio_dk_nrf5340_cpuapp.conf
index b55471d8b62..3f605b57919 100644
--- a/tests/bluetooth/tester/boards/nrf5340_audio_dk_nrf5340_cpuapp.conf
+++ b/tests/bluetooth/tester/boards/nrf5340_audio_dk_nrf5340_cpuapp.conf
@@ -12,6 +12,7 @@ CONFIG_LOG_BUFFER_SIZE=4096
 CONFIG_RTT_CONSOLE=y
 CONFIG_LOG_BACKEND_RTT=y
 CONFIG_LOG_BACKEND_RTT_MODE_DROP=y
+CONFIG_LOG_BACKEND_RTT_MESSAGE_SIZE=256
 CONFIG_USE_SEGGER_RTT=y
 CONFIG_SEGGER_RTT_BUFFER_SIZE_UP=4096
 CONFIG_LOG_BACKEND_SHOW_COLOR=n
diff --git a/tests/bluetooth/tester/boards/nrf5340dk_nrf5340_cpuapp.conf b/tests/bluetooth/tester/boards/nrf5340dk_nrf5340_cpuapp.conf
index b55471d8b62..3f605b57919 100644
--- a/tests/bluetooth/tester/boards/nrf5340dk_nrf5340_cpuapp.conf
+++ b/tests/bluetooth/tester/boards/nrf5340dk_nrf5340_cpuapp.conf
@@ -12,6 +12,7 @@ CONFIG_LOG_BUFFER_SIZE=4096
 CONFIG_RTT_CONSOLE=y
 CONFIG_LOG_BACKEND_RTT=y
 CONFIG_LOG_BACKEND_RTT_MODE_DROP=y
+CONFIG_LOG_BACKEND_RTT_MESSAGE_SIZE=256
 CONFIG_USE_SEGGER_RTT=y
 CONFIG_SEGGER_RTT_BUFFER_SIZE_UP=4096
 CONFIG_LOG_BACKEND_SHOW_COLOR=n
diff --git a/tests/bluetooth/tester/boards/nrf54h20dk_nrf54h20_cpuapp.conf b/tests/bluetooth/tester/boards/nrf54h20dk_nrf54h20_cpuapp.conf
index 29139393b46..5bb1c4d8284 100644
--- a/tests/bluetooth/tester/boards/nrf54h20dk_nrf54h20_cpuapp.conf
+++ b/tests/bluetooth/tester/boards/nrf54h20dk_nrf54h20_cpuapp.conf
@@ -12,6 +12,7 @@ CONFIG_LOG_BUFFER_SIZE=4096
 CONFIG_RTT_CONSOLE=y
 CONFIG_LOG_BACKEND_RTT=y
 CONFIG_LOG_BACKEND_RTT_MODE_DROP=y
+CONFIG_LOG_BACKEND_RTT_MESSAGE_SIZE=256
 CONFIG_USE_SEGGER_RTT=y
 CONFIG_SEGGER_RTT_BUFFER_SIZE_UP=4096
 CONFIG_LOG_BACKEND_SHOW_COLOR=n
diff --git a/tests/bluetooth/tester/boards/nrf54l15dk_nrf54l15_cpuapp.conf b/tests/bluetooth/tester/boards/nrf54l15dk_nrf54l15_cpuapp.conf
index 29139393b46..5bb1c4d8284 100644
--- a/tests/bluetooth/tester/boards/nrf54l15dk_nrf54l15_cpuapp.conf
+++ b/tests/bluetooth/tester/boards/nrf54l15dk_nrf54l15_cpuapp.conf
@@ -12,6 +12,7 @@ CONFIG_LOG_BUFFER_SIZE=4096
 CONFIG_RTT_CONSOLE=y
 CONFIG_LOG_BACKEND_RTT=y
 CONFIG_LOG_BACKEND_RTT_MODE_DROP=y
+CONFIG_LOG_BACKEND_RTT_MESSAGE_SIZE=256
 CONFIG_USE_SEGGER_RTT=y
 CONFIG_SEGGER_RTT_BUFFER_SIZE_UP=4096
 CONFIG_LOG_BACKEND_SHOW_COLOR=n