Default [Q] T-Mobile Tether, data keeps failing randomly

Hey,

I have a Nexus 5 that is set up to basically act as a router using wireless tethering. I live in an area where I constantly have full-blast LTE that is usually above 30Mbps. For about a month, everything's been great until this last week. Now, every few hours my data connection gets killed completely after anywhere from a few minutes to a few hours after tethering has been running. Data stops working on all tethered devices as well as the Nexus 5. Entering airplane mode and then resetting the WiFi tether fixes the symptoms, and if that fails, restarting fixes it.

I've disabled wireless_tether_dun (sp?), switched to IPv4 and I sometimes use a VPN that passes through all network traffic through the VPN. Even with VPN disabled, the data drop keeps happening.

I know there are so many things that can be going on, but has anyone else noticed this recently? I'm wondering if it is a hardware issue, a signal issue, or perhaps T-Mobile has changed something on their side of things that is killing my somewhat obvious abuse of their network.