Hosting/serving

Hi all
Heres 1 for you! Having problems serving on the net ( Games ) Any chance you can give me any help as to the setting side of the router? as i get 100% loss when hosting. It as nothing to do with my firewall as i sometimes get a unsecured signal upstairs which is very low and i can serve on that signal for a while... naughty naughty...lol
If you can help it would be much appreciated.
Many thanks