I just finished to configure my Minecraft server and everything was working as expected until one of my fried tried to connect, I play with other 5 friends but he is the only one that can´t connect, we have a world with around 70 mods.
When I checked the console I noticed this message "[23:48:30] [Server thread/WARN] [minecraft/MinecraftServer]: Can't keep up! Did the system time change, or is the server overloaded? Running 2088ms behind, skipping 41 tick(s)"