Hi Stefan,
I’ve encountered the same issue back in 2023 when I’ve installed my first system with a Multiplus 3000 GX. It seems, there is an isolation issue with the USB-port of the internal GX-device. Tried grounding of the shield an all other suggestions. Nothing had worked so far.
A cheap USB-isolator from Ebxx or Amazxx made the trick, Since then, I had no outages.
Best,
Wilm