connection to ff14 goes chaotic every certain time everyday

i dont know how to explain this but this has happened for like a month now.

every 19:00 pm until 21:00 pm my connection to ff14 suddenly goes bad, like when i ping my server (tonberry) it just full og RTO and the latency goes up to 150ish (normally is at 100ish)

at first i though this is my internet, but it wasnt. when this happened my internet is doing fine, i ping to other website/server, youtube, forum site, etc. i even ping to NA server and the ping is normal (not even one RTO), it only happen to tonberry server during 19:00 pm until 21:00 pm which after that it goes back to normal.

can someone help? iam not even sure if this from my end or from the server or anything else