As of recent my dedicated server doesn't appear to be showing up on the gamespy server list anymore, despite the command box saying " is now running on ".

If it helps to say, I'm running the haloceded.exe app with Wine on an ubuntu machine, however I have not had this problem before. Would appreciate some help/input :)

Cheers!

you need to open up some ports for your server to communicate with gamespy and the internet.

i haven't used ubuntu before, but there should be a way somehow to try all the stuff mentioned in the articles below:
http://hce.halomaps.org/index.cfm?nid=239
http://hce.halomaps.org/index.cfm?nid=237

I doubt that's the cause because it used to work fine and none of my network settings have been modified since then. Not to mention I have my firewall disabled (both computer and modem-wise).

did you change your modem/router before this happened?
also, disabling firewall wouldn't help either.

No, I have not modified any settings of any kind since it used to work. I should probably state that I had issues running the app all of a sudden, which may offer an explanation (ie. a bug or some confliction with Wine/Ubuntu software, as strange as that might sound).

1. update your versions of wine and ubuntu to the latest versions, go google them.
2. reinstall the app for the server after step 1.
3. check if your init.txt file for your server has sv_public set to 1.
http://hce.halomaps.org/index.cfm?nid=314