It's a hardware problem, isn't it?! (Router not working)

The setup:

Cable modem hooked up to a Belkin N+ wireless router. Modem-router environment is 192.168.100.x. Router-wireless environment is 192.168.2.x.

The symptoms:

  1. For several weeks, the Internet connection has been flaky, cutting out at the modem about once a day. This throws the router, which fails to reconnect (I’m sure it used to). I frequently restart it to get things back up and running.

  2. Until this Saturday that is, when the Internet went down for about an hour. Restarted the modem - but no Internet. Called the ISP support line and discovered the modem had adopted a 169.x.x.x local address for some reason. Unplugged everything and got the modem back online.

  3. Now the router won’t connect to the modem at all. I can hook the computer to the router admin screen at its local address, both wirelessly and with cable. And I can hook the computer up to the modem by cable and get online (which it what I’m doing now).

I’ve done a “factory restore” of the router, but it still won’t see the modem.

If I can plug the computer into the modem and get online, does it follow that I should be able to plug the router into the modem and it should be able to get online, or is there something I’m missing? Or is it, as I suspect, a coincidental hardware fault at the “Modem” socket on the router?

What type of ISP are you using for broadband, DSL or cable?

I ask because the possibility that comes to mind is that you are on cable broadband, and the cableco ISP ties your account access to the MAC address (to prevent unauthorized access to their ISP services). Perhaps your account is tied to the MAC address on your computer’s ethernet card, and you previously had your router configured to “clone” your computer’s MAC address. When you did a factory reset, you lost this configuration. If this is the problem, you need to find the MAC address of your computer’s ethernet card (the one that works when you plug it straight into the modem), and then configure your router to use the exact same MAC address (on its WAN port).

If that isn’t the issue, it may help others to know what country and what service provider you are dealing with for broadband.

And by the way, your description in points 2 and 3 don’t make complete sense - your modem has no role in any IP level connectivity. It doesn’t have an IP address.

Hey, thanks AZCowboy. I am on broadband (UK Virgin Media, formerly NTL - still NTL infrastructure if that helps).

I have never had to clone the MAC address - it’s not a requirement of the ISP.

Regarding the modem not having an IP address, I don’t know what to call it then - if I look at my “default gateway” via ipconfig when the laptop’s hard-cabled to the modem, I get the address 86.30.x.x. which I am guessing is DHCP-derived by the modem from the ISP? Or is it from the ISP itself? And if I want to access the modem’s admin screen I go to 192.168.100.x in my browser.

I don’t suppose there is a link light that would indicate ethernet (network cable) connectivity between router and modem? There should at least be one on the router, I would think.

Good point. It’s flashing orange, indicating lack of connection.

I should point out that when the cable is disconnected, there’s no light at all. When it’s plugged into the modem and router, the router ethernet light indicates an error; the modem ethernet light is on as normal.

There you go. If you’re using a known working cable then it’s likely a bad port on the router. But don’t take my word for it, I would call the manufacturer to confirm.

That was my original thought, hence the thread title.

But… it seems a coincidence that the modem connection crapped out at the same time as the router. Could the port on the router going bad be responsible for losing the IP address from the ISP?

Also, would there be any way to test that port with the computer, or is it designed purely for connections to a modem?

One thing I don’t think you mentioned, have you been experiencing the aforementioned “flakiness” of your internet connection since connecting straight from PC to modem?

No, it’s been totally solid.

Oh, and I think you should be able to test the port by connecting straight from router to PC, however this connection might require a crossover cable so I would not consider it a definitive test.

Okay, I’m going to say 99.9% percent chance it’s the router. I don’t think your internet problems are a coincidence at all, it sounds like the router’s been your culprit all along.

Hmm, I don’t think I do. Furthermore if the port is shorting something out, I don’t want to risk breaking my ethernet card.

Thanks for all the advice by the way!

No problem. I have to run now, hope you get it resolved.