LB1121 with CGNAT Hangs and Requires Factory Reset

[UsernameLimits]

My setup is for an IoT application.  I have the following configuration:

LB1121 with ATT IoT SIM in IP Pass-thru mode

Unifi USG

Unifi switch

IoT devices (many)

The setup works perfectly for about an hour, then slowly degrades.  The degradation instatiates as lost network connections.  Monitoring software shows that the USG loses its internet connection after about an hour, but successfully reconnects.  The lost connections increase in frequency over time, eventually occurring every 5-10 minutes.  After 24-36 hours of being connected, finally, the LB1121 just quits working.

Logs show that the ATT IoT CG-NAT changes the assigned private IP as often as every 5 minutes, which the LB1121 appears to lose the ability to handle over time.  The eventual failure is that the LB1121 won't reconnect to the cellular network.  Power-cycling the LB1121 doesn't work, either.  The device must be factory reset and reconfigured. 

I have repeated this cycle several times while trying to debug this problem.  😮 

This has all the hallmarks of a memory leak in the LB1121 firmware.  Has anyone else experienced this issue?  Have any ideas for a solution?   (I have also submitted a support ticket, but am afraid that Netgear will blame it on Ubiquiti and vice-versa)

Thanks!