Having problems using a modded server

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    I'm having problems joining a friend's server, it is a modded server and I'm sure I have the correct mods with the correct versions, other friends don't have any problems joining, it's just me. I attached the error it gives me when I try to join, I also want to note that I sometimes can enter, it has let me enter a coouple of times but rarely, I can't manage to join consistently, any help would be great.