I have 1GB ethernet and I have the exact same issue. If my phone is on my wifi and I get a notification there is motion on one of my cameras and then use my phone to try to connect, it never works. However if I turn off the wifi and try have my phone on the cellular network, it will work fine. It is like Ring won’t let your phone connect to them from the same IP as a camera that is sending recordings to Ring at the same time.