RAK2013 - SSH kicked out suddenly and now refusing connection

I have a raspberry pi that is connected to Verizon - we01.vzwstatic and the connection seems slow. I have others with the same configuration that have been running for weeks with no problem but this one seems to be reluctant to work. The network seems to lock up. Today I was SSH’d in over the LTE when it kicked me out and now is refusing an SSH connection. The unit is about an hour away so I can’t get in locally right now. The rak2013 still seems to be up and running and connected to Verizon because my attempt to connect is not timing out it is actively rejected.

This happened previously and I had the unit brought back so I could look with it and I found no issues while it was here. Put the pi back in the remote location and after about 1.5 hours it locked up and is inaccessible again. I’m completely at a loss as to why it would do this. I’m going to run out to the remote site and see if I can see what is going on out there but before I do is there any thoughts on what to check? Is it a problem with the hat or a problem with the raspberry pi?

My thoughts are this:

  1. Maybe it’s over heating? - and if so is it the Modem or the pi?

  2. Maybe there is poor signal quality? - How do I check the signal strength when I get there?

Any other thoughts are much appreciated. I’m completely confused because I’m running the same image on the raspberry pi with the same iptables set up and i have 3 or 4 that are running and this one that is just not happy.

Thanks in advance.