Herelink air unit-need some help

Hello friends, I’m assembling a FPV system with a matek h743slim flight controller and a Herelink air unit 1.1 on an ardupilot. However, I can’t figure out why there’s no telemetry. When it comes to configuring telemetry in the mission planner and installing the Herelink on the flight controller, everything is done correctly. However, I sometimes manage to connect to the mission planner using telemetry, but most of the time, I can’t. I’ve been searching for the cause for a long time, and I’m tired. I need your help.