LAN keeps dropping IP

mikidi-kikidi

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Jun 16, 2008
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18,510
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.
 

Tcinator

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Jun 25, 2014
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So, your "LAN" is not dropping. The synchronization between windows and a modem can be a bit of a bitch. Since your modem has an IP, and no LAN DCHP capabilities enabled, sometimes the PC that is directly connected won't properly apply the IPv4 config given to the modem. So, to avoid any possible oversight, turn off the PC, unplug the modem from the wall (power). Wait 15 seconds, plug back in. Call your ISP, ask them to send a refresh signal to your modem, after that's complete, fire up the PC. If all goes according to plan, the modem will pull a fresh config, and push it to the PC when it boots. This SHOULD work. Might not. Hope it does...
 

mikidi-kikidi

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Jun 16, 2008
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Thanks for the response. I have not called the ISP yet (I might tomorrow if I have time in the morning) but here's some more info on what happened tonight that made me think it's probably not an issue on the ISP side (although I'm pretty clueless):

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?