To add my experience so far:

Having been stuck in Quarry Mill for over a day unable to do anything, calling a Mount would not even result in an audible whistle, talking to anyone or attempting to teleport would result in a complete loss of control, unable to accept friend requests or anything for that matter before eventual 90k error would throw me out. I was eventually able to leave the area while connected to the game servers via a wireless hotspot on my phone.

As of now, I'm able to play fine for the most part, barring the occasional disconnect and 90k error when teleporting between areas in particular, but they can also happen randomly. I am able to do duties and quests no problem.

However, I have had to return to Quarry Mill due to MSQ progression once, and resulted in exactly the same symptoms as before.

I'm a UK player on Leviathan.