Simple quiz today: what do you do when you get the message "The server is not accepting new connections at this time".
Of course, you know that this message has to do with the setting of the AOS to Reject new clients (https://technet.microsoft.com/en-us/library/hh433538.aspx), but today I wasn't playing with that setting.
However, what I was doing was running some automation scripts, and among the tasks was a line to clear the sessions: user sessions and server sessions. For those of you who don't know, there is a table called SysServerSession that holds the current running session of the AOS (or AOSes).
So what happens is that the AOS looks for that line when trying to create a new user session, and if it's not there, well, you can't get in, of course. The fix: just stop and start the AOS - it will create a new line (session); just like you would also do this when you pressed the Reject new client in AX.