I registered for the forums just to complain about this very issue.
I've played this game for over 970 hours and never experienced anything like this before, a disconnect every now and again, some latency issues every once in a blue moon but nothing serious.
I live in Europe, Macedonia but play on the US Hyperion server and so far my experience with the game has been remarkably positive, what little latency issues I had were resolved after I installed the leatrix latency fix, but that was months ago.

Stuff really started messing up yesterday afternoon when I was doing my daily alex roulette, had a good run through sunken temple hard with a great PUG when the game started lagging and I found myself booted with I believe a 1000something error, but don't quote me on the number it wasn't a 90k error since I believe i took note of that.
Tried for an instance one more time, same thing, then the 90k's started, at first the game runs nice and smooth, lag free for about 10-30 minutes then severe lag kicks in and you get disconnected with a 90k.
Don't make me waste my time on port forwarding and other such utter nonsense when my game has been working flawlessly for over 970 hours now in course of over 9-10 months, plus all my ports are open and good.

I thought things had cleared up this morning, but no sir, after about 30-40 minutes of playtime or so I found myself on the 90k screen once again.

IF this is an issue with my ISP they won't resolve or bother to fix it, I can guarantee you that much, but since all other online games work flawlessly and my internet is perfectly fine it's clearly not on my end.