Unplayable lag at same time each night

[Owls_Neck]

Since Sunday, every night around 1am EST, the game becomes unplayably laggy. This only affects Final Fantasy, and it doesn't seem to be from DDoS attacks since my friends I'm playing with are unaffected. Chat will just randomly not update, people walk around in short bursts while freezing every half-second, dungeons are even worse, and I get much more frequent 90k errors. I've read one recommendation to use a VPN when this occurs but that had no effect. What can I do? I literally cannot play the game when this happens, and I often don't have time to just play during the day instead. It's very frustrating.