Connection issues for Yu-Gi-Oh Duel Generation games

Hello, I'm facing a problem when I try to enter my Yu-Gi-Oh Duel Generation game. When I open the game, I'm notified that I can't play because I don't have an internet connection, even though my Wi-Fi and 4G are always on, but it still doesn't work. I've visited several forums, but none answer my question, considering that I've spent a lot of money on this game and I would really like to find a solution.