Cannot play COD 4 LAN over wifi

[Japster]

Me and my mates are trying to play some COD 4 LAN via wireless, but once I start the LAN server they cannot see me at all. If I connect one of the pc's via LAN Cable, they can see the game, but no games are available via wireless. We are not running any mods. Is there a fix for it.

We have all the firewalls switched off.