Phone just disconnected from WiFi
Yup, the Moto X4 really doesn’t like IPv6. I’d have to send it to them, and the replacement may or may not work correctly on WiFi.
Not sure it completely disconnected, just lost it’s internet access. The WiFi icon would most likely be gone if it disconnected. There was an X and it said LTE.
Switches to LTE if the wireless connection isn’t working, turn your modem off and you’ll see. The local network can still work, but whatever IP it calls home to, if that doesn’t work it switches to LTE. So maybe the call home IP went down.
If you could force it to not switch to LTE, then you might be able to use IPv6.
Search for WiFi on the Moto X4, the last entry is what you want, click it, and it’s nowhere to be found. Search in Settings.
Switch to mobile data automatically, to bad the setting doesn’t actually exist where it says it does.