LAN keeps dropping IP address

Ok so all of a sudden these last few weeks my W7 computer has started having an issue I last remember wrestling with years ago:

my internet goes down and comes back after I've reset the cable modem a few times and spammed the "Diagnose/Repair" option in my adapter settings. After a few tries it usually gets the connection back up and gives the "LAN doesn't have valid IP configuration - Fixed"-message when it finally repairs it.

I have no router, just plug my desktop directly in to the cable modem. I just have the Windows firewall and the cable modem is in bridged mode and has literally worked flawlessly for the last five years. Yet now it constantly does this, what gives? I haven't really changed anything (I don't think).

I've tried fiddling with a few other adapter settings and stuff I stumbled at googling (disabled IPv6, did the flushing out ips and get new ones in cmd) and installed new drivers but it keeps happening, what gives? I feel like a moron.

 

1. ISP problem
2. Modem problem (you did mention the modem is 5 years old)
3. Bad cable between computer and modem
4. NIC in computer needs newer driver

Obviously the easiest thing to try is buying a new cat cable and replacing the one you have to see if things are sorted out. Next would be to see if there us a newer driver for your card.

Before I call my ISP, I power cycle the modem. Disconnect the power from either the back of the modem or the wall plug and wait one minute. Then plug in and watch the lights turn on. I have 4 green that turn on one at a time and the last is a flashing amber. When they are set, I fire up the computer and see if I can surf. (I actually have a router and print server in the mix so it takes me longer to get 3 pieces of hardware settled).

 

1. Could be, I've been meaning to call them up. Probably should tomorrow.
2. Seems weird it'd work flawlessly for 5+ years and then just start malfunctioning in this manner (dropping the IP), but what do I know. I'll exhaust every other option before looking into a hardware purchase.
3. Tested multiple different cables
4. Installed a bunch of different network-related drivers from my mobo manufacturer

I have done what you suggested multiple times. That's what I usually do when this issue has come up; keep restarting the modem and spamming the Diagnose/Repair thing on Windows. After a few minutes it comes back up. But then at some point it loses the IP again.

 

Of course the NIC could also be going bad.

 

I would literally suspect the modem or the ISP network if you already had gone yourself to the troubleshooting on your side that far.

 

Thanks for the replies. Some more info.

Tonight the connection again went down and now even after multiple modem resets and trying to release and renew the IP on console it just wouldn't come back up. It was giving the error message about LAN not having an IP configuration or something like that.

I pulled out my old laptop I hadn't used in years, turned it on and plugged it to the cable modem. The connection immediately came up. After this I took the ethernet cable and put it back in my desktop and what do you know, it worked.

What does this tell you?

 

If the laptop can keep a connection and the desktop can not, then the NIC in the desktop looks more like the problem bit of hardware.

 

When you say "NIC" you are in effect talking about the LAN adapter?

or is there something software-related I could try to do to troubleshoot it?

I'm using the integrated LAN adapter on my mobo

 

NIC stands for Network interface controller aka the port you plug the ethernet cable into.

I don't think it's software; I think it is hardware. If the integrated ubnit is dying, then you can install a card with a port on it.
example: http://www.newegg.com/Product/Product.aspx?Item=N82E16833166004&ignorebbr=1