Just built my friend a new system. Had it connected to my home network just fine, could get on internet and all that (connecting to cable internet through my computer). He just got highspeed cable internet at his house, hooked up directly to the modem, and is getting "limited or no connectivity" and no internet. Just spent a couple hours trying to troubleshoot over the phone to no avail. Tried everything I could think of: checked all physical connections - led's are blinking where jack is plugged into comp, power cycled modem multiple times, tried to repair connection in network connections - could not renew ip, tried network setup wizard to no avail, went to properties -> tcp/ip -> properties and is set to obtain ip automatically. Nothing is working. Can't try a different ethernet cable until tomorrow. Also tried netsh winsock reset command. Any suggestions? Mobo is Biostar NF61V and OS is Windows XP. Don't know what the modem is, Motorola something or other. Please help!
I think the DHCP was the problem. I took my router to his house, hooked it up, and it connected to the internet instantly. I just couldn't understand why we could hook it up at my house directly to the modem with no problem. We have the same ISP and the same model of modem. He went out and bought a router though, so problem solved!
Some ISP's will provide modems with basic DHCP server. Probably someone configured your modem for you before, and your friend's modem was working with DHCP server disabled. If that was the case - his PC would receive APIPA address (you can view it running ipconifg /all command from command line) and if you see Ip address of:
169.254.x.x to 169.254.255.255 then it usually points out lack of DHCP server on the network or in very few cases a hardware problem.
All you have to do then is manually assign IP address to your network card (usually 192.168.1.x range) and log into your modem/router via web browser: default addresses like: 192.168.1.1, 192.168.1.100, 192.168.1.254 etc (depends on the model) and turn DHCP server ON.
Then you turn your network card back to automatic mode and it should receive address from the modem/router.