The infamous Skele DC.

I agree. Theres a simple way to test too.

Someone who constantly dc's, would you mind going into a mini dungeon, but instead of traditional "barely moving" ultimate spam. Either cycle the map and cast it, or just for a change, train with your summon+(CL || Paralyze || AR). If you don't disconnect while moving all over the map, we may have found the issue.

I'm pretty sure the bot check happens regardless of how you are training.

This seems like a pretty reasonable guess. I haven't gone a full length of time at skeles without dcing at least once (almost always reset it after the first hour or so for whatever reason).