My experience of MG dealers (although limited to just 2 dealers) is that their technicians have very limited training. The first dealership I was working with (where I bought the vehicle) have stopped doing diagnostics at that branch, which led me to changing to a more local dealer. The more recent dealer technician was much more confidence inspiring and solved the problem within hours of my leaving the car (including getting authority for the warranty repair).
If your dealer is correct and that MG stopped the server, we would all be experiencing the same symptoms. I am not currently near my car, so I cannot confirm if I am experiencing the same. I can however confirm that iSMART has access to the car now (10:45 8th September). Maybe someone else here can confirm that their connectivity experience in their car is normal.
If everyone else’s is normal, it appears that your T-box may have a fault (this was the case with mine, my symptoms were slightly different in that everything appears to work except there were no responses to iSMART).
It is possible your dealership may have misdiagnosed the fault.
First thing though, have you tried a factory reset from Right screen, Settings, System.
Next try the unbind and rebind. It is possible that the activations may have become deactivated.
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