Gary has a Motorola G5 plus mobile phone with T-Mobile and after his phone updated, his WiFi calling option won't connect. Leo says the culprit is that the update broke that feature, and it is only a matter of time before Motorola puts out a fix. Leo says that his router may also have an issue with it. He may need to log into the router through the browser and reenable port forwarding or open port option with UDP enabled. Check out this link - https://forums.lenovo.com/t5/Moto-G5-Moto-G5-Plus/Oreo-8-1-ER082-Unable-.... This solution fixed it for some users.