Hey,
that issue seems to be having a lot of people and it has been already told people many times but as i see you didn't check any other threads so i will help you with it.
Explanation
"unsupported protocol version XXX" means that a server does not accept the current version of the launcher you are on. as many people have the issue on this server with 107, 110 or 210 which means they do have a version which is not supported on pika-network. this means that you are using 1.9, 1.9.4 or 1.10 which we do not allow on pika-network.
How to fix it?
You can use from 1.7 till 1.8, probably the server you are joining does not support 1.9. Try to use 1.7.0 or 1.8.0 launcher.
If you need more information please follow by replaying on this thread.