Anyone Else Getting POL-0260 And POL-0011 Errors?

This would not necessarily disconnect you from TF2; ffxi has very little tolerance for lost packets. A modern game can easily recover from any missed packet, FFXI will ***out if your client fails to respond at the wrong time. Dropped packets will be mostly unobservable during web browsing, as the amount of data requested is generally small in comparison to your bandwidth.

That said, strings of those errors do seem to appear at times. I d on't think it's necessarily SE's servers, and I doubt making a post will change anything. If it's actually a problem on their end, JPs will be reporting it anyway.

First I would try another router, as it's most likely your router.

Next up would be https://www.wireshark.org/

Quite frankly I've never gone to that level, I'd probably check your NAT settings first, I know older routers didn't play nicely with natting.

It could absolutely be an ISP routing issue. You could try using a VPN.