I have two Starlink HP units and they have done this on my BR2 Pro 5G for over a year. I filed a ticket with Peplink support, and they were never able to figure it out. Their suggestion was to put a switch in between the Starlink and the BR2 which isn’t a long term solution.
The only way I’ve been able to get this to work is ensure that the BR2 boots up first, then reboot the Starlink HP. 99% of the time this works.