It seems to be a rampant problem now. Anyway, this thread is the closest to identifying the problem. I'm not suggesting you use any of the VPN programs recommended, as there can be some security concerns if they don't use cryptographic tunneling. But it seems the most probable cause for both the sudden increase in lag and disconnects. S-E seems to have posted a thread collecting IP and location information, probably to locate the problem route.
http://forum.square-enix.com/ffxiv/t...on-the-problem