mine works fine on cs, my xbox has static ip and reserved in dgl-4500. wired connection
maybe you have a strict nat? if you have a public ip in your router, try doing power cycle and try cs if it works.
Here are a few of my settings.
FIREWALL
Enable SPI-unchecked
NAT ENDPOINT FILTERING
both-Endpoint Independent
Enable UPnP-checked
WAN PING-off
Enable Multicast Streams-checked
Advanced Network
WAN Port Speed : 100
Gamefuel
disable Dynamic Fragmentation :
Automatic Uplink Speed : checked
your xbox to 127 priority, the rest pc and laptops at 200.
my firmware is 1.15 and hardware A1
if your modem is some type of community network, ask your provider to set your QoS to 104 in your modem.
one more thing, use OpenDNS as your dns server, and if you upgrade, you can block ads on xbox live by going to your opendns settings, Web Content Filtering- Always Block: rad.msn.com
you can also filter internet by Proxy/Anonymizer, Adware, and other stuff,
this helped me on facebook third party ads, you can still see primary ads from facebook though.
goodluck.