Did you disconnect just the data cables, turn off the power, or both?
Duh. How do you know that the router gets an IP address? The only way you can do that is to actually login to the router. That means your unspecified router is mostly working.
Does your unspecified router have:
A log output?
A "status" page?
Some internal diagnostics such as ping?
What IP addresses are on your two computers? If it's 192.168.xxx.xxx or something similar, the DHCP server in the unspecified router is working. If one of these has a routeable IP address that you would expect to find from your ISP, then you have the cabling all screwed up between the modem, router, and clients. If it's 169.254.xxx.xxx, then DHCP didn't work and something MIGHT be wrong with the router. You might want to try a grand reset of the router before spending money (last resort).
Come ISP's authenticate by the MAC address of the client. You may need to login to the router, and clone the MAC address of the workstation that did the original configuration.
Also, try bypassing the router and just connecting your windoze box to the cable modem. Don't leave it like that for long, but that will confirm that you have a functional connection. Be sure to power cycle the cable modem (and later the router) when you juggle connections as it has to load the new MAC address of its connected devices.
I can connect to the router from every computer because I can access the router's web interface. It has a status, but no ping and a limited log.
My router gets an IP because the router status shows it. Also shows the DHCP and DNS server. There is a test connection button but it always fails. The test tries to open the Netgear web page.
IP's in the clients are: 192.168.xxx.xxx, set as static IP's or dynamic
I did a full reset of the router
There is a MAC address validation from my ISP, so they will notice about the router (they charge more if you have one). I have the option "Use default" which uses the router MAC address. If I use the computer directly, I can't connect, because the MAC address is not the default one.
I have 2 more computers that connect wirelessly, with the same problem. I can see the other computers, but they can't go beyond the router.
I'll try the netsh commands and see if that works, otherwise, I'll try with a new router or the computer directly.
It worked, I re-connected my computer and I got internet connection, of course my ISP had to reset the modem and the MAC address. I reconnected the router and I set to give the computer MAC address, and it worked.