Board Thread:Bug Reports/@comment-29716003-20160826010216/@comment-27219153-20160826012840

The "illegal extra prefix" is normal. I get hundreds of them upon starting a server and it works just fine. From what you are saying it sounds like other people are able to connect, but one person imparticular is not able to connect, correct? If that's the case, the problem is most likely on the client side, not server side.

If you can provide more information about the server, such as lotr version, is it using forge or a different jar, other mods?

I think the most useful information would come from the client who cannot connect. Another question that you could ask is: Is this person able to play singleplayer or connect to other servers?