VST System Link has been deactivated because of too many errors! HELP

I am on Cubase 11, using Mac OSX 10 & Apollo Twin.

The apollo twin has a dodgy connection so if I move it a little it disconnects. So thats fine - I just turn it off and on again. But it entirely kills my project and does something so I can never hear audio again on that project.
If I create a new project - no problem. but if I open the existing project I get nothing. I can see the levels bouncing but nothing comes through the Apollo. Even if I switch ASIO to Built In Audio - still no sound.
I have selected Universal Audio Thunderbolt 1 for both ASIO input & output. Tested with VST System Link Active and not Active.
When I compare the ports set up list to a project that does work - I see that IN 2 & OUT 2 are active.
On this project that has no audio it’s showing:
IN Universal Thunderbolt 1 - Active
IN Universal Thunderbolt 2 - Inactive
OUT Universal Thunderbolt 1 - Active
OUT Universal Thunderbolt 2 - Inactive

I keep getting the error message: VST System Link has been deactivated because of too many errors!

I really need to finish this project. Any help massively appreciated.

I think VST System Link is for linking/networking multiple different audio devices. So you probably shouldn’t be using the VST System Link at all. I did some work in a studio (Pro Tools Software) with some Universal Audio interface with similar ‘dodgy connection’ problems with the computer. Turned out it was cabling issue. Replacing Thunderbolt cable with a shorter and higher quality cable (e.g. not the cheapest) resolved the issue.