I don't know why you guys are like, talking to him about game server connections, when literally for Solo the instance should just still run.
The way Deep Dungeons Solo are ran is poor and ruins morale for your player to even continue on to play the game.

Whoever designed this, should reconsider changing how disconnecting or crashing effect the run.
There is a reason why most players don't even attempt these achievements, or challenges is because of this harsh restriction.
The feedback has been for years very negative for this issue.
We should strive for change for this content, not debating about how our connections work, or hating on one another. the game suppose to bring fun, not frustration, specially after 7+ hours of work wasted.