You can try this: In Windows, type in the search box "CMD" without quotes, click run as admin, in the Command window that pops up type " ipconfig /flushdns " without the quotes.

Make sure to logout of the game client first.

If you still get the error, I would unplug the modem for 60 seconds then plug it back in, and then try logging in.

If that doesn't work, you could move the character data folder or copy it, don't delete it, and login and see if its fixed, if it is then move the folder back/overwrite new one, and login and see if it kicks you, if so then the data for that character is corrupt.

Or you can try using a phone as a hotspot, connect your computer to it via hotspot and try to login.

Worth a try.