Disconnecting again and again
Same issue here.. unplayable at the moment.
First, make sure that you contact support:
https://help.guildwars2.com/anonymous_requests/new
Second,
It’s possible that the problem is anet, since you have eliminated various options, but the bad news is: nothing fundamental changed in their architecture in the last patch or anything like that. Traffic profile is still pretty much the same, suggesting that there is maybe some intermediate point between you (and your two ISPs) and anet that causes the trouble.
https://www.pingplotter.com/fix-your-network has a good guide for identifying where the problem is, but if you have trouble with that feel free to post screenshots from it and we can help work out where it is.
Unfortunately, the Internet is built in a way that [many] companies handle your traffic… There are lots of places that the problem could spring from that neither end is responsible directly for.