After 5 months of stable operation with my Blackberry 9810 with 220.127.116.114, it started rebooting continuously. It took several rounds, but I noticed the problem happened just as the rebooted Blackberry synced to WiFi. If I moved fast, I was able to turn off the radio in the reboot process before WiFi started.
I discovered that it wasn't the WiFi connection, but the start of WiFi Calling (an additional layer of syncing with TMO servers after the WiFi data connection is going). So if I'm connected via WiFi to a router with ports blocked in a way that WiFi calling can't work, but a WiFi data connection is working -- no problem. If the WiFi calling links up, BOOM, the Blackberry goes into a reset loop.
I tried updating the OS to 18.104.22.1689, hoping the problem would go away. I wiped both data, applications, and the old OS off before loading the new OS. I did restore the old data.
Same problem -- the new OS boots and is fine until I attempt a WiFi connection that links to WiFi Calling. It is certainly the WiFi Calling since it happens as the WiFi Calling permission box appears in the new OS load.
This just started this week after I did a routine Atl-Shift-BackSpace reboot.
Since WiFi Calling is supposedly all software-based, I assume this is software, not hardware. But TMO wants to replace the phone.