router died, but why?

October 13, 2005 10:09 PM

My router doesn't work anymore. It used to...

I have high-speed internet access (3Mbps) via Charter digital cable. For the past 2.25 years I've been using a D-Link 704P (wired) router to share the connection between my PC desktop (running win2k), my laptop (winXP) and sometimes my G5 & mini (running Tiger). Worked flawlessly.

About four weeks ago we had a series of power outages and the router power light wouldn't turn on anymore. Thinking I was all smart I determined that the power supply died (voltmeter) and ordered a new one. The router power light came back on, but then the internet connection was crap - the first page I clicked would half-ass load up and subsequent pages would fail and time out.

I thought perhaps the router really was dead so I bought another D-Link 704P because I liked the way it worked. As soon as I hooked it up it did the exact same thing - first page petered up, then all other pages timed out or errored with "can't find server". I poured over the D-Link website and tried every single troubleshooting tip listed and there weren't that many because these routers are pretty auto-magic. A call to D-Link's tier-2 support suggested that maybe the (new) 704P was defective.

It should be noted that if my DPX110 cable modem is plugged directly into any one of my computers I get the internet connection that I'm used to. But I want to share 'cause that's what I learned in kindergarten so the router has to work.

I returned the (new) D-Link 704P and bought a Netgear FR114P. Hooked it up and I'll be damned, it does the exact same thing as the 704Ps did. First page, then no more.

Today I: tested each and every Cat 5 patch cable, verified the dynamic IP settings in the FR114P, tried inputing my ISP's DNS severs into the router, double checked the network settings on each Windows box, did the whole ipconfig /release /renew thing, reset the cable modem - all to no avail.

Charter says if plugging the modem into the computer works it's not their problem.

Sigh. Could anyone maybe just point me in the right direction? Is it possible Charter can determine if you're using a router and crap it out so you have to use their own gear? What else could it be?

posted by shino-boy to computers & internet (12 comments total)

To know avail? what ip addresses are you pulling? When you ping a site, does the name resolve to an ip address? Can you ping ip addresses? Have you tried assigning static ip addresses to your machines, and specifying the dns servers in each computer? router 1, DNS server 2, and so on... Is it loading the first page because it is cached? If you have successful pings, try doing a tracert to see where it is stalling at.
posted by AllesKlar at 10:19 PM on October 13, 2005

Did you clone the mac id of your old router?
posted by AllesKlar at 10:20 PM on October 13, 2005

Charter in my area was once an EXTREMELY sketchy network, with very, very weird DHCP servers. They would not work properly with my Linksys BEFR41 router. I'd get a firmware update, and things would be fine, and then they would regularly change things in an apparent deliberate attempt to break the router. Eventually they wised up, and at this point the network in my area is both standards-based and pretty solid, good enough for Vonage service. (for a long time it wasn't). It took forever for them to get it right, but it's good in the Atlanta area now.

If you're in an area where they're still doing the stupid stuff, you might need to use MAC address cloning. That's where you get the MAC address from the computers that work on the link, and program the router to use one of them. That makes it 'look like' the main PC you normally use.

MAC addresses are layer-2 ... they run under IP. Each network card on a network segment has a unique MAC address... in theory, every network card in the whole world has a unique MAC. When DHCP gives out an IP address, it assigns it to a particular MAC. In other words, the DHCP server knows that 'this particular network card is given this address'. If you lost your settings on your router, and you had MAC address cloning before, suddenly your DHCP server may think you're a stranger, and won't give you a good IP address. It may be giving you a fake one, that will work well enough to get to Charter's own website, but no further.

Worth checking.
posted by Malor at 10:26 PM on October 13, 2005

Another thing... connect your PC back to the cablemodem, verify you're browsing properly, and then do an ipconfig /all in a command prompt window. Write down pretty much all the information you see. (including the MAC address, which is in the format AA:BB:CC:DD:EE:FF).

Then hook up the router and see what address it's given. It should, most likely, have the same numbers for the first three octets. If it's wildly different, particularly if the number you're given is in the 10.X range, the 172.16.X-172.32.X ranges, or the 192.168.X range, then you're being refused a 'real' number, and MAC cloning is almost certainly your problem.

If MAC cloning doesn't fix it, then post back with the info you get from the PC versus what your router is getting.
posted by Malor at 10:32 PM on October 13, 2005

saw this on another site whilst googling the cable modem model number:
(url to this info, and here's another forum thread about that modem)
-------------------------------
Author: datatech229 (---.tmodns.net)
Date: 08-31-05 09:56

witch webstar you guys using??

We have webstar modems and all of ours work fine on any router.

DPX100
DPX110
DPC2100

Try and see if it will pull any ip address from the modem. The modem will issue an ip address of 192.168.100.1 if you unscrew the coax cable line from the modem and reboot it without the coax line in it still. Leave out the coax line and see if the routers will pull a 192. ip from the modem. if not you guys need to look at a different modem.
---------------------------------

hope that helps
posted by tweak at 10:32 PM on October 13, 2005

I have read that sometimes on large ISPs, depending on what address you get via DHCP, your routing can be vastly different. If there is an overloaded or failing router in charter's network, it could be that when you get a DHCP lease from the MAC address of your Dlink, you end up going through that router, whereas the DHCP lease you get when the computer is directly connected might give you an IP address from a totally different pool that takes a different route.

So, when it works fine directly connected without the Dlink, note the IP address given in your DHCP lease, and do a traceroute to some common site. Now connect the Dlink, see what IP address you get from DHCP, and try the same traceroute. If the paths differ greatly, and you see large delays on the second one, then you probably need to clone the MAC address of your PC in your router, so that it will get the same IP address as the computer when it's directly connected.
posted by Rhomboid at 10:47 PM on October 13, 2005

I've seen exactly that behavior in Charter in Georgia, Rhombold... two disparate networks with entirely different address ranges and routers, but on the same wire. It didn't last that long, so I think it was just for a transition to a new network range, but they do know about and use this trick.
posted by Malor at 11:38 PM on October 13, 2005

I would suggest connecting directly to the cable modem with one of your computers, doing a release.....but DO NOT RENEW

Then without any IP addresses from Charter, connect your network up as you want, then renew your IP on the router (via your router management software du jour).

My thinking is that when you connect your router while one of your computers has the real IP, then your router does not get it. Your computer and your router are competing for the real IP address (shared uses a fake IP)
posted by unceman at 10:04 AM on October 14, 2005

This morning I:
Verfied that the router was cloning my desktop's MAC addy.

Wrote down all the good settings when the modem was connected directly into the computer and checked them when the modem was plugged into the router - they almost matched.

Turned on UPnP.

Still didn't work. The only inconsistency I now notice is that when the modem is plugged directly into the PC, the default gateway and DHCP server's IPs are different - when the modem is plugged into the router the two IPs are the same (192.168.0.1, the router). Is that bad? I'll see if I can set the DHCP server in the router...
posted by shino-boy at 10:09 AM on October 14, 2005

Sorry for the long delay on the reply, have been tied up.

Something is definitely amiss here.

You say they 'almost matched', but I'm a little confused about what you're comparing... from your wording later, it sounds like you may be comparing the settings on the PC with and without the router in the loop. Those will definitely be different. What I'm trying to determine is if the router's external address and settings are the same as the PC's address when it's directly connected. If you can post the actual IP addresses you're getting in both cases, that would be useful. For privacy, you may want to obfuscate them... in an A.B.C.D address, replace A and B with something else. Just be consistent in your replacements. If you are inconsistent, troubleshooting will be very hard.

A DHCP server is a per-wire thing. A router breaks a network up into separate wires. You have one wire coming in from outside. Either your PC is directly connected to that, or you put the router in between, creating a separate network wire with a separate DHCP server. The router gets its external address via the external wire's DHCP (like your PC would), and PROVIDES DHCP for the internal wire.

The router should, in other words, get real IP addresses for its external interface, its router, and its DNS servers. If your router has any method of doing ping testing, I'd suggest pinging around a bit after it's connected to make sure it's working. This part is crucial. You MUST make sure that the router is connected and getting a valid IP address before you can do any more troubleshooting. Do you understand how to find this out on your specific router?

As far as your question about DHCP and the gateway being the same on your internal network... yes, that's very normal. Your router is both your gateway and your DHCP server. Each of these is a per-wire thing. With some brands of router, your DNS server will also have that same address again. This is all fine. All of these functions are lightweight and easily handled, in a home network, by a single tiny box. ISPs usually break these services across multiple machines to improve reliability and share the load, but that's not necessary.

I normally leave UPnP off. I haven't seen it be particularly useful, and it's yet another service that could theoretically be compromised. It definitely adds a potential layer of complexity, another way the settings can be changed without your knowledge, so I'd recommend leaving it off until you have things working.
posted by Malor at 4:46 PM on October 14, 2005

Did you get this going?
posted by Malor at 4:19 PM on October 15, 2005

Well, I finally fixed my "router"...

After pulling my hair out for a few more days I decided to try one more thing - attempt to setup the router using my laptop instead of the desktop PC. Well what do you know, with just the laptop connected , the internet connection worked. Plugged my Mac mini into the router. Worked. Plugged the desktop in. No more internet. Unplugged the desktop. Internet's back again.

So now I knew it was my desktop PC that was the problem, not the router. I figured the onboard NIC had gotten damaged during the power outage, even though repeated testing of the LAN connection from within win2k yielded no error or warnings. I installed a brand new Ethernet card and... the desktop still would not connect to the internet.

!

To make an already long and boring story short and sweet, I reformatted my c: drive and reinstalled a fresh, clean copy of win2k. Good news - internet connection between all computers and router is now happy. Bad news - Using the fdisk and format commands in DOS, I got a little confused and also reformatted one of my data drives, as they all look alike. D'oh!
posted by shino-boy at 7:10 PM on October 17, 2005