Can't play with a friend online (Minecraft)

Played minecraft with a friend on Tlauncher by Radmin. Installed the mods I created the world everything was fine. Then after 3 days he cannot enter the world and the error "io.netty.channel.Abstractchannel $ annotatedconnectexception connection refused no further information gets out. I watched all the videos on YouTube, nothing helps. The firewall cut out, the router restarted, tried to play through Hamachi and And it all started after I played with another friend. I don't want to reinstall the game, I'm sorry for the worlds. Help someone!