Kurz : Problem taucht bei mir nur bei folgenden EA reproiduzierbar auf :
EA Volatility Factor 6
EA Wallstreet Asia V1.3
Ausführlicher
I can reproduce the problem and might be stated the proplem at least symtomatic:
If adding one of the following EA i can reproduce the error to all VPS except one VPS (the one from roboforex 
):
EA Volatility Factor 6
EA Wallstreet Asia V1.3
If added one can non rescan/reconnect.
If closing EA windows and restarting everything fine.
It's repeatable-
It might be a thing between Windows and a library somehow used by MT4 and/or the DLL of those EA.
EA that do not show the problem : myfxbook EA, mt4i autorestart. Both not dealing but having dll files. Wallstreet recevovery EA also running fine, it's from the same company than the Wallstreet Asia EA what is strange.