LM1200 Disconnects from Internet once a month

I have an unusual problem and I am curious as to whether other LM1200 users or similar experience this problem.

I have an AT&T sim card in my LM1200 with 40GB data limits. My billing period ends on the 25th of the month, at which time all my data limits reset. I use the LM1200 and Google WIFI routers to provide internet to the location - there are not other alternatives.

On the 26th of each month, at about 8am EST, my LM1200 drops the internet. I can usually go into the Admin console and tell it to reconnect, and it does. This works ok when I am there, but this is a remote site, and I am often not present, and cannot reset the link.

1. Does anyone else have this problem or are you familiar with it?

2. Any suggestions for resolution?

3. Any ideas how to troubleshoot?