Pulse Secure VPN - Keeps dropping every few minutes

You mentioned working fine for “45 days” which I assume is meant to say no changes made to your TMO service, TMO gateway, and your laptop during that period. Based on this assumption we can eliminate the following possibilities:

• Some folks have reported problems with VPN due to TMO home internet gateway changing public IP on a regular basis creating a conflict for VPN services that require static IPs. However, in your 45 days of no issues, TMO gateway would have changed IP multiple times but your VPN still worked.
• You don’t mention any change in bandwidth or general connectivity which would rule out something changing on your local cell phone tower. 
• Your current firmware version is the latest but it was pushed out in April so the firmware did not change during your 45 days of operation.

Assuming that company A made no changes to your laptop, then one must conclude something changed on the configuration of VPN provided by company B.

A couple questions you can ask to get to the bottom of this:

• Does the VPN settings require a static IP? TMO IPs are not static.
• Does the VPN settings require an MTU of 1500? TMO uses 1420.
• Does VPN support IPV6? TMO uses IPV6.