The receiver's port is a poor choice, or two telemetry set-ups collide

What ArduPilot says:

• …: passthrough telemetry conflict on SERIALN
• …: running on non-DMA serial port

“running on non-DMA serial port”: the receiver is on a serial port without DMA, the hardware that moves bytes without the processor's help. CRSF and ELRS run at about 420,000 baud or faster, and without DMA bytes can be lost; processors of the H7 family do not need it and never show this. “passthrough telemetry conflict on SERIALn”: RC_OPTIONS bit 8 asks for Yaapu passthrough telemetry over the CRSF link, while port n is also set to FrSky passthrough (SERIALn_PROTOCOL 10). Only one can have it, and the CRSF one is not started.

What to do, most likely first

1. The receiver is wired to a UART that has no DMA on this board.

   CheckThe Board & Wiring Planner shows which serial ports of your board have DMA.

   FixMove the receiver to a port with DMA, set that port's SERIALn_PROTOCOL to 23 and the old one to -1, and reboot.

2. Passthrough telemetry is asked for twice: over CRSF and on a FrSky port.

   CheckRC_OPTIONS has bit 8 set, and the port named in the message has SERIALn_PROTOCOL 10.

   FixKeep the one you use: set the named port's SERIALn_PROTOCOL to -1, or clear RC_OPTIONS bit 8, and reboot.

Parameters to look at

Where to do it:Board & Wiring Planner