Some questions / suggestions
1. Have you recenly installed any Add-in's or other third party software? If yes, please detail.
2. Have you recently made any changes to your network settings (router or WHS)? If yes please detail.
3. Are you using DHCP or static IP-address for your WHS? If static, please try using DHCP. In router DHCP settings please make sure primary DNS server is pointing to router (gateway address), not outside address and also make sure router is not using
primary DNS suffix
Personally I would still think this is a router (settings) issue. Please try on your router (after saving current config or writing down current values):
a. remove all portforwarding, then check again
b. reset router to default settings, then check again.
Henk Panneman - http://www.homeserverweb.nl