Wireless SIK Repeater

I use Holybro SIK v2 telemetry and I would like to build a repeater described in Repeater for Wireless Ground Station Connections. I tried with an ESP32 based board and an ESP8266 WIFI module and ran into the same problem. If I connect the WIFI modules directly into the pix32V5 flight computer, both WIFI modules work.

If I connect them to the Holybro telemetry radio, both WIFI modules transfer the messages from the UAV but no commands are transferred to the UAV. QGC responds with Vehicle did not respond to command: (whatever command has been sent). The behavior is identical for px4 and Ardupilot. The SIK radios are working correctly when connected with UAV / QGC.

Any idea what’s going wrong?

Many thanks

I can give the answer to myself. Disabling flow control solves the problem.