diff --git a/boards/px4/fmu-v5x/nuttx-config/nsh/defconfig b/boards/px4/fmu-v5x/nuttx-config/nsh/defconfig
index b1e3752e2b7..afed466ea21 100644
--- a/boards/px4/fmu-v5x/nuttx-config/nsh/defconfig
+++ b/boards/px4/fmu-v5x/nuttx-config/nsh/defconfig
@@ -250,7 +250,7 @@ CONFIG_UART5_IFLOWCONTROL=y
 CONFIG_UART5_OFLOWCONTROL=y
 CONFIG_UART5_RXBUFSIZE=600
 CONFIG_UART5_RXDMA=y
-CONFIG_UART5_TXBUFSIZE=1500
+CONFIG_UART5_TXBUFSIZE=3000
 CONFIG_UART7_BAUD=57600
 CONFIG_UART7_IFLOWCONTROL=y
 CONFIG_UART7_OFLOWCONTROL=y
diff --git a/boards/px4/fmu-v5x/nuttx-config/p2_base_phy_LAN8742Ai/defconfig b/boards/px4/fmu-v5x/nuttx-config/p2_base_phy_LAN8742Ai/defconfig
index c463a159c14..74f0f7b9c3f 100644
--- a/boards/px4/fmu-v5x/nuttx-config/p2_base_phy_LAN8742Ai/defconfig
+++ b/boards/px4/fmu-v5x/nuttx-config/p2_base_phy_LAN8742Ai/defconfig
@@ -251,7 +251,7 @@ CONFIG_UART5_IFLOWCONTROL=y
 CONFIG_UART5_OFLOWCONTROL=y
 CONFIG_UART5_RXBUFSIZE=600
 CONFIG_UART5_RXDMA=y
-CONFIG_UART5_TXBUFSIZE=1500
+CONFIG_UART5_TXBUFSIZE=3000
 CONFIG_UART7_BAUD=57600
 CONFIG_UART7_IFLOWCONTROL=y
 CONFIG_UART7_OFLOWCONTROL=y