Hamachi Problems

Seeing as i can never get port forwarding to work, i turned to hamachi. It worked great, but then a week ago I changed my router to a Linksys WRT400N. I’m running a default configuration, no port forwarding shit yet, and i’ve got Bit Defender 2010. I checked Bit Defender and can confirm thats not blocking it. Hamachi seems to work fine, but my friends can never connect to my Gmod Server. Any ideas?