I'm currently experiencing the same issue while attempting to get back on Excalibur (Primal). The game disconnected me while I was going for a solo, unsynced stroll through Sastasha, right before entering the Captain's Quarters.

I've attempted logging back on, but no luck so far. I've occasionally seen queues pop up before being able to make my attempt, hence I guess there are other people trying - and most likely having trouble - at the same time.

The pattern of the client being locked into "Poor" connection quality after a failed log-in seems to hold (even if shifting to a different node, i.e. from Primal to Chaos) just as in Sugata's case; I've also seen the 10105 error code being returned from time to time, though code 90002 seems more prevalent.

Will try again later, hope this helps in diagnosing the actual problem. My Internet connection seems to be working as expected in every other respect.