reconnection error means the games clients are out of sync. Cheating can cause this also. One players came is doing things others dotn do and it throws them out of snyc. When i played on the orig servers some maps would cause a reconnection error when a player with gap generators lost power or the gap gen was destroyed. On those maps it was due to glitched terrain , like hills that are not properly made as well as misplaced nuke reactors. I used to fix them all the time. On cncnet there is that redzones map that recones if the player at spot one makes gap in the top left corner and loses power. I looked at the map and cant see any irregular terrain. SO, I'm not 100% sure what causes it on that map.
The sync.txt files are status dumps pf all the units and players in the game at the time it went out of sync. The game makes these, not the cncnet client.