You're fine. Getting a disconnect, server side or not sucks, and I can understand that.
I still think 21 days for a cooldown is fine, as 7 days would be too short.
Nikola has also been reworked as well, meaning that if you get a server crash you can simply re-challenge him again. If you disconnect due to your internet though, that's a different story.
If you failed, just come back better prepared.
But, that's just my opinion.