I get this problem while playing or when I'm at the character menu. It also happens no matter what latency i have (even when It's about 50-150 ms)
It always starts with the game freeze, but sometimes i get the input lag before this. It lasts for about 4-5 seconds and then I get the "Disconnected from the server" message (and get back to the login screen).
I don't know what to do. My usual internet speed is 91 mbps. There was a time when I've been DCing every 10 minutes! It's a big problem for me because I can't go to the BG or instances normally.
