LB1120 stops working - increasing in frequency

Hi- Have an LB1120 (tmobile) and love it. Unfortunately it will hang and lose the LTE connection and show no bars on the unit, just power and activity on the ethernet side. A reboot doesnt help.

The cure is to do a factory reset (rest button for 10 seconds) and immediately I get bars and signal, then reconfigure to work with my local network. SIM card is brand new and seated correctly.

This (historically) has happened about once every 3-4 months, now its happening every 3-4 days. It's running the latest firmware and the fix is easy (takes 10 mins) but it happens at inopportune times.

When it runs, I runs like a champ, but the "no bars" does not correlate with any TMO outage as my phones still run and are fast. The 1120 just shows no bars and "
broadband disconnected" on the control panel. The factory reset immediately cures the issue. Ideas?