TECHNICAL ISSUES

How determine which player is with the issues? I was battling with a guy today in a championship and my DS showed an error with the conection. I don't know if the error showed first in my DS or in the DS of the guy (he did say that showed in mine, but I don't believe cause he was looking arround and not to DS when the error occured), so, how to determine? I would have won if this don't occured...