This is almost always caused by the information being incorrect. Either the Server IP address, the Server Port # or the password is wrong.
If you are connection with Spacial Audio SAM 2/3/4 and are entering http://184.108.40.206 for the IP address,
instead try entering numerical IP for your server 220.127.116.11 instead.
Make sure when entering the password that the caps lock is in the correct position.
This error can also be caused by the server malfunctioning and you should immediatly open a support ticket.