Telemetry not work under Serial Port 3 AKA USART 2 in ardupilot

ArduCopter
,
1

I’d recently linking openIPC aka wfb-ng linked from Rx & Tx into UART Tx2 Rx2 under MATEK H743 V3 Flight controller via INAV without any problem with Telemetry working by using MAVLINK protocol.

The problem seem to be happened only on ardupilot with telemetry, why?
I’d configure like this,

SERIAL3_OPTIONS = 0 (23 also not working)
SERIAL3_PROTOCOL = 1 (2 for mavlink)
SERIAL3_BAUD = 115 (115200)

2

I’m using this line “/dev/ttyS2” to link into Flight controller which is workable on INAV, how about in ardupilot?