I have had pretty much the same Verizon problem as danglo.
I used my tethered phone while traveling in around labor day and it worked just fine, as it has for about 5 years (also).
I am on another trip and tried to get on the internet a week ago and got an error to the effect "Server does not respond. Contact support and give this error number." No error number was stated.
Two days ago I tried again and got the error message "Server name and password not recognized on this domain"
These error messages are from memory becasue they go away very quickly.
I have kept my old Verizon phone and plan mainly because of this internet feature. I will be home in a few days and work the problem. Maybe it is time for a change.
Fortunately, there is a lot a free WiFi around now.