I agree, the boss should have been ideally prevented from spawning in the first place while the login server was down, with a system message extending the boss re-spawn window. Though this is only advisable when the window is very near closing time, as it was today when there was issues with the login server. If there is a problem 20 hours into the window, and there is an issue, you can safely move the spawn timer 2 hours without telling anyone.  
	Second best option, despawn the boss shortly after he spawns. Before anyone get in any real attempts.  
	Doesn't really change the fact that the boss was yours. We were struggling with coordination, people were all over the zone, few on discord, and only 2 of us were from my guild. You could have gotten him on either of the two first attempts.