This post is basically for my own reference but if it helps someone else that’s great.
On the server open up a command prompt and type ipconfig /all this will display a list of settings. You need to check to see which is the Default Gateway. In this case I needed my Default Gateway to be the Domain controller for my Domain, and I needed to change it. To do this you need to go to the Network and Sharing Centre. This can be reached by going to the Control Panel (my server was Windows 2008 R2) then Network and Internet, then Network and Sharing Center.
On this panel you will should see a Local Are Connection. Click on this and then go to Properties. On this screen look for Internet Protocol Version 4 (TCP/IPv4) and then click on Properties. This shows a screen where you can change the Default Gateway and Preferred DNS server. I altered both to point to my desired Domain Controller. I then saved the changes.
I was then able to go to the System window for my server, this can be reached either through Control Panel -> System and Security -> System or in Windows Explorer right-click on Computer and go to Properties. On this screen you will be able to ‘Change Settings’ to specify the Domain you want your server to join.