@Daniel1 A few of us are having the symptoms you’re describing (see Z-wave stopped working from V2 Hub). Is it just your switches and dimmers that stop responding? All my z-wave sensors (motion and open/close) work just fine, but none of my switches are responsive to commands from the app. All locally controlled actions through the smart lighting smartapp still work flawlessly, so I don’t think it is a signal issue.
I received a reply from support yesterday that said they were having issues on their end that might be the source of my problems, but they were unclear as to whether the issues were resolved or, if not, a timeframe for resolution.
It is very frustrating to say the least, but I would hang in there until this is resolved. I was a former Wink user as well, and when SmartThings is working properly, it blows Wink out of the water.