Having disconnect issue aswell.
Every night, between 1 am to 3 am (GMT+1), I get R0, and 9/10 times I get disconnected. Last night, it managed to recover and stay on. There is nothing on my PC that runs during that time, and my router is not rebooting or anything. Its also properly set up with ports.

Another thing, I can play the game actively (as in, not being afk), for an whole day with just a little lag now and then. But when I let my character stand idle in Jeuno for bazaaring items, I get disconnected within 40 mins. It happens each and every time I let it stand idle.
And yes, I have turned off the "Auto-disconnect upon idle" option in config.