We have two Apple Store iPhones, one a 12, one a 12 Mini. Both have LTE enabled and work with LTE/5G coverage when we are out and about. ISP is Spectrum; our connection typically speed tests at >300 Mbps down and 19-20 Mbps up. It’s been rock-solid for other purposes all day, including steaming media. Phones use WiFi for other purposes without problems. We live on the island of Kauai, HI. Router is an ASUS RT-AC68U. All devices have most current non-beta system software. All have been rebooted in the process of troubleshooting this. T-Mobile plan is postpaid unlimited. WiFi Calling is essential for us since we have marginal to no wireless coverage at home. WiFi Calling on T-Mobile has worked reliably since we switched to T-Mobile in the fall of 2020.
Sometime recently, WiFi Calling has stopped working. Both devices show green wireless antenna, “No Service”, grey wireless antenna, “T-Mobile WiFi Calling”, green wireless antenna, “No Service”, [rinse and repeat on about a five second cycle]. The phones both installed a “T-Mobile Service Update” several weeks back; at that time, I noticed that my battery was not lasting nearly as long, and the largest consumer was “No Cell Coverage”. (63% over the last ten days, none in last 24 hours.) I don’t know when WiFi Calling stopped working; I did put on the latest iOS security update several days back.
Any advice? Unreliable WiFi Calling (previously on Pixel/Verizon and Pixel/Google Fi) has been the bane of my wireless existence for several years now. I thought six months or so with T-Mobile with reliable WiFi Calling was a good sign. Now, not so much.