Because the mod alters game files, it desyncs from any unofficial private servers. You can only play against the AI.
: A common community tip for faster collection is to repeatedly challenge a duelist and immediately surrender; you receive one random card from their deck for a loss (versus three for a win), which is often more time-efficient than playing full matches. Modern Alternatives Duel Generation Yu-gi-oh Duel Generation Mod Unlock All Cards -UPD-
You can still earn cards by winning duels against AI opponents in the offline campaign. Because the mod alters game files, it desyncs