I am having the same issue. Wifi strength in garage is excellent, router is on floor just above it. I have an IP reserved for the opener on the router. Using an upgraded Amazon gold plated USB cable as well - cable that came with it was too short.
I can reset the opener and it will show online for a time in both the app (Android) and on the web. After resetting the unit works great for a time. Comcast is my ISP. Any ideas whats going on?