Just recently my xbox live has been dying while im playing games etc. I check my router and the light is still on, i check my pc and find i can browse no web pages. When i do an xbox live connection check it tells me my dns has failed. After about 5 minutes of no response suddenly my connection jumps back into life and everything is fine. Until of course it happens all over again. What exactly can i do about this, using the fault checker it doesnt really seem to cover my problem area. Am i right in thinking DNS is something plus nets end? The DNS on my xbox 360 is setup to automatically asign a DNS by the way. Any help would be much appreciated.
I don't know if will help you in your case as it sounds like you're getting a total disconnection if the PC can't browse the net either, but there's some things you can do to help with the connection to Xbox live.
Give your 360 a fixed IP address in the network settings (of the dashboard) instead of it being on auto (the IP address that your router automatically provides should be a fine one to stick to). This way it doesn't fluctuate if your router automatically assigns it a different one at another time.
Then set up the router configuration so these ports are forwarded/allowed through the firewall of your router:
This process can vary depending on the router and it might be called something else. For instance my Netgear router required me to set them up as 'services' and then apply them to the 'firewall rules'. You need to make sure these "rules" are allowed/set to the IP Address you've fixed for the 360.
If you're unsure, a google of "port forwarding" and your router type should help you find instructions.
Since setting up the port forwarding I've had a lot less problems. I still get disconnected every now and again but it's quite infrequent.