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://220.127.116.11 for the IP address,
instead try entering numerical IP for your server 18.104.22.168 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.