Nothing has been changed regarding connectivity, the servers weren’t changed at all. Connection speed normally isn’t an issue unless you set the upstream rates to values close to or higher than what your service provider delivers which doesn’t apply as yours are much higher.
What changed on your end? Which Cubase/Nuendo version do you use and with which version did it work well? Did you change latencies or anything the like? The release of VST Connect PRO very certainly has no impact on your operation, the only changes were that along with the PRO version, also a new SE version has been released.
If the problems persist, let us know what your versions, system, and VST Connect settings are and we’ll try to sort it out.