Hi people

As the title says, I am unable to connect to the modmyi repo while at home on WIFI whereas when I am out I can access the modmyi repo over the 3G network. This started happening around the start of the year, no changes had been made to the router. It is a bit frustrating as I almost always use cydia only when I am at home. I dont have trouble with any other repo AFAIK and can log into modmyi from my iMac on my wifi network.
I have iPhone 4 iOS 5.0.1 jailbroken with redsnow 0.9.10b5

Any ideas as to why this is?