Server has to be STOPPED. If there's anyone In-Game, simply write them a message through the Console using "say WiseHosting: message"
Have a look at the extra ports and subdomains that the admin has potentially set up. Take a screenshot of both just in case you need to add/update these on the new node! This will be useful later on.
Open up the admin (game) panel of a server you'd like to move, find "Manage" tab from the top. From there, you can find a "Transfer Server" button.
IN CASE OF JUST THE SERVER IP CHANGE: Have a look at which node the server is currently hosted on (Admin Game Panel of the server, main page). Pick another node in the same location.
NORMAL TRANSFER TO ANOTHER LOCATION: Pick any node on the new location
Pick the values for allocations (ports):
default allocation = primary port
additional allocations = the additional ports (listed under Network tab). If possible, pick the same ports that the customer already had configured/used. Then you don't have to reconfigure the voicechat/dynmap etc.
If everything is correct - click on CONFIRM and start the transfer. If the picked node is full, choose another one.
Have a look at the servers Console - it should be in installation mode, and displays transfer information to the Console. The transfer has been completed when server IP is updated