I just wanted to post a quick tip that i discovered yesterday.
My Internet Service Provider is being bought out by another company and it seems they are doing some behind the scenes work on their end. My internet connection started acting up and then suddenly completely stopped yesterday.
After 30 minutes on the phone with tech support the conclusion was that something was wrong with the router. When i got off the phone I was left with one pc connected directly to the cable modem and my router completely out of the loop; tech support told me to contact router company for a replacement router.
Of course i never believe anything tech support people say, so i did some experimenting.
The router was not retrieving an ip address for some reason.
What i tried, which worked instantly, is to go to the router settings and CLONE the MAC address of my pc.
So i guess for some reason they were blocking my router from getting an IP from the network, and this tricked it. I'm sure the experts here could provide a better explanation, but I thought i would post it just as something to try if you have a similar problem.