I'm not too familiar with all the networking options but are all your ports on the box filled? There have been many reports over on BBC about boxes with all ports hooked up causing problems.
Other than that, have you bypassed all the network stuff and just hooked it up direct to one unit only and tested it out that way? Might be worth a try to with each unit to see whether the E-box is causing the issue.
You might ask this question over there on the HBird forum as well.
Edit to add: Have you checked all your voltages with everything running? Hooked to it's own power grid or is it all coming off your starting battery? That also a question that you'll be asked by anyone trying to help.
Last edited by 6poundtest; 07-08-2023 at 05:38 AM.
Yes, I was talking to myself; sometimes even I have to ask for expert advice.