Trouble accessing JF using server name

[kiwichick]

On the server you SHOULD be able to set a static IP on the server itself instead of relying on the router.

Thanks, I'll give that a go. I've had a look at the IPv4 properties to set a static IP. It says I need to enter an alternate DNS Server but I have no idea what to enter. Any suggestions? Is an alternate even necessary?

ETA: I've set the static IP and left the alternate DNS server empty. Rebooted the server PC and everything looks good. Thank you so much for all your help, and answering my endless questions.