The winboard.nl server seems to be up and running. I could connect two WInBoard running on the same computer through it (using the default password). The second p2p that starts on the same computer leads to an error message that the port is already in use, but that is only for listening to incoming calls on your own computer. So it would still work for making the outgoing call to winboard.nl, and you can ignore the message.
Perhaps the server somehow still thinks that your password is still in use, because a connecton died silently, and it thinks one user using that password is still connected. (Although I don't think this is likely; when two people get connected, and one of them disconnects, the server then disconnects both, and knows the password is available again.) 'You could try another password.
The same thing happens to me.