1. Both phones are listed as fully supported for video calling. LG G4, S7.
2. Works perfectly if both phones are set for, and calls routed, via cell. Video quality is almost like HD - even when cast to big screen via Chromecast.
3. However - When I set my phone for wifi calling, the video call drops after 20-30 seconds. Get an error message. (Can't recall exact wording.) Can make voice calls over wifi w. no problem. Wifi connection is 90+Mbps UP and Down.
I had assumed that all video calls (since they are data) would use wifi automatically no matter how you set the preferred routing for voice calls. That is not the case.
Best answer by tmo_chris
Oh no! It sounds like this issue is more intermittent while on WiFi and works over the cell network just fine right? If this is the case, the issue is not going to be with the phones or the T-Mobile network leaving the WiFi as the only variable. I know your speeds are fast enough to maintain a call but there may be something else causing the quality of your WiFi to dip while on a video call causing it to drop. I would recommended reaching out to your ISP and seeing if they can run some tests on your connection while you place a video call to see if they can find any abnormalities.