Latest QGC connection drops and interference with control on Herelinl

I have recently tried to upgrade QGC on my Herelink to the latest version using the instruction here. I have a herelink 1.0, and the standard QGC shipped is 4.08, which resulst in parameter warnings and the camera controls don’t work correctly with newer arducoper versions, so I am stuck at arducoptrer 4.1 at the moment.

At first it looked like everything had worked OK, but then when I connected to my drone - Cube Orange running arducopter 4.1 the staus was OK for a few seconds, the dropped to “connection lost”.
More worrying was that the radio connection also appeared to become unstable. Furtunately I was testing on the bench, but camera movements were smooth before but became stuttery and would hang, or stop completly, whihc made me thing something was affecting the comms link too.

Has anyone else seen similar issues and found a work around, or any pointers are very welcome?
Thanks