MR6110 suddenly has packet loss after a month of use

About a month ago, I bought the MR6110 from ATT. It worked amazing for gaming, the ping stayed around 30-60, so no latency issues or packet loss, or anything like that. Now it is a month in to having it, and I am experiencing packet loss, especially at night, making for a terrible gaming experience. I have tried factory resetting the device and rebooting it, which did nothing at all.

Also, this is happening with ONE device connected, so no there is not network congestion.

I was going to try port forwarding for the game I play, but when I try port forwarding, it says "maximum ports exceeded" and does not allow me to. Does anyone have any kind of solution? Is this likely an issue with the router, or maybe ATT is throttling me? I haven't even come close to my data limit.