Further details:
Only happens when wi-fi calling is turned on. Tried different routers on different network and same problem with each. Have a second Lumina 521 that works ok. Go figure?
Either a hardware problem with Nokia 521 #1, or an APP confict on said device. Funny that All Network Service both t-mobile cell and wi-fi are killed - hard.
Am reluctant to do a factory reset. Much customization on phone.
