Motorola Moto G — No wifi or cell connectivity

A few days ago my Motorola Moto G 2nd gen stopped connecting to both Wifi and cell network. Until this happened the phone was fine. Phone functions that don't require any connectivity - gallery, camera, contacts, etc. - continue to work fine.
The phone is running Android 5.1. My cell service is from Page Plus, and at the time I bought the phone in 2014 the vendor flashed it for Page Plus.
I've tried rebooting the phone, and also tried running the phone in Safe mode.
The last OS update was in April 2016. Without connectivity I can't get an Android update over-the-air, and I've been unable to find a way to download a newer version of Android to my PC and then transfer it to the phone. I put Motorola's MDM on my PC, but when it checks for an OS update, I've only gotten the message "Server busy. Try back later."
I have not yet tried a Reset To Factory Settings.
Any suggestions would be appreciated. Seems to me the only possible software fixes are either:
1) Upgrade to a later version of Andoid, if I can figure out how to do it via my desktop PC
2) Reset to Factory Settings.
Any tips on how to update to a later Android, without going over-the-air?
Also, if I Reset to Factory Settings, would that "unflash" the phone, such that it would no longer be compatible with Page Plus?
Many thanks in advance.