Is my cable modem or PC killing my router?

[BCSteve]

So recently I thought my Asus RT-N56U wireless router was crapping out. It would randomly "die"... sometimes after 2 minutes, sometimes after 12 hours (usually 10 to 30 minutes) after a reset. Here's what "die" means: wireless pc shows the SSID still and states that I'm connected to a network but without Internet access; wired or wireless pc has no internet... can't log into the router, or even ping it. The only evidence its even there is the SSID still showing up. Fine... crapped out router, right? Under warranty, no big deal... have an RMA pending. Yay.

But!!!

So I dig out my old DD-WRT based Linksys WRT54G. Plug everything in, fire it up... back in business. FOR TEN MINUTES! Then its "dead" too. Almost exact same symptoms. It still shows on the SSID list and still says the wireless client is connected. The only difference is with this router, it doesn't say there's no internet... there's just no internet. And as above, still can't log into router's admin or even ping it (or any other device on the network). Solution is a power cycle, same as the Asus.

Two routers with the same problem... no way that's just coincidence. Is my cable modem killing my routers? A virus on one of the pc's? I kind of doubt the latter. I've tried it with just the laptop (wireless) connected and I've tried it with just the pc (wired) connected. And in the case of the pc, I (clean) reinstalled Windows which would have wiped any virus... but same thing happened.

Any advice at all? i'm perplexed.

 

[somms]

By using 2 separate wireless routers and you are having the same problem, you have already troubleshot the issue to something prior to the routers. It sounds like a cable modem/ISP issue and NOT with the wireless router(s).

 

[coxhaus]

If 2 routers are having the same problem it is probably not the router. I would try another cable. If you don't have one, they are cheap. The next thing I would try is to look at your modem. I had a modem go bad and it was causing strange results. I don't know a good test for modems but you might try to take it out of bridge mode and see if you can get some stats on the modem. I finally bought one and it was the modem. Maybe your provider will give you one free.

 

[BCSteve]

Thanks guys. I guess by the same logic, I also ruled out the cable. I was lazy when setting up the 2nd router so instead of running the same cable I used with the Asus, I grabbed another shorter one and set the router up on the floor next to the modem. (ie. I used a different cable for the 2nd router).

I convinced the ISP to replace my modem next week. In the meantime, its out of bridge mode and I'm using their built-in router hoping that may be more reliable.

 

[BCSteve]

Although, I gotta say that they are 100% convinced its my router... stating it "has to be" since I can't even ping my own router from the wired (or wireless) pc, and that's a direct connection between the pc and the router and has nothing to do with the modem. I can't argue the logic there. I suggested that maybe the router is misbehaving and causing the router to shut down... he just laughed that kind of "you have no idea what we're talking about" laugh

Whatever. once I get the replacement modem hopefully I'll have my answer.

 

[fizikz]

It does seem strange that 2 routers would have the same problem. Did you try setting up the router(s) without connecting to the modem and see if the not-able-to-ping-router problem shows up in an hour or so?

If it happens, then you know it's not (just) the modem; if it does not happen, then you can be more confident it's not the router.

 

[BCSteve]

No, I haven't... that's a logical step though. I'm out of town for a few days so I'll try it when I get back. in the meantime, I had the cable company change it back to a router (from bridge mode) and removed the other router from the equation. Since they did that last night, its been fine.


Call it a shot-gun spread-the-blame tactic, but I already have the ASUS out for RMA replacement and the cable company is replacing the modem with a new model next week... so really, other than curiosity, further testing at this point is a bit... well, pointless, since all the variables are changing.

 

[Fraoch]

You may also want to investigate whether the router(s) are properly getting the WAN IP address from your ISP via DHCP. Many routers behave quite strangely if they don't get a public IP address. Obviously you will have no Internet access but the router may also lock up.

It should still respond to pings through, but you never know.

That's the only thing I can think of that would persist across two routers. It should be addressed by swapping the cable modem out but I have heard of ISPs where their DHCP servers fail or may run out of IP addresses to send out.

 

[BCSteve]

So it turns out to be.... "none of the above"

It wasn't the router(s), it wasn't the pc(s), it wasn't even the modem... it was the cabling upstream from the modem. The tech came and didn't replace the modem as I was expecting, but instead stripped out the cable that comes from the outside of the house to the point where the modem connects to the wall. His explanation was that poor cabling will cause the router to restart multiple times and eventually that causes some routers to respond like there is a DoS attack (he said that was one possible explanation) and it can cause all sorts of havok on a network. So in a way it was the modem I guess.

Fingers crossed anyway. If the problem persists (so far its been 5 hours with no trouble) then he'll swap the modem.

- Steven

 

[Fraoch]

Huh! Well, keep us informed!

 

[BCSteve]

Weirdness continues...

OK, so a couple days ago I reported (well, what I reported... two posts up). All seemed good for the first day, then in the morning we were back to the same symptoms as before (almost!): I went to the laptop (wireless) and saw I was connected to the network but without Internet access. As before, I could not access the router admin page or even ping it. I did have an IP address and ipconfig /all showed everything as normal... just like before. So I think, "ah crap, no difference". But then...

But then, I go down to my office where my wired pc is. I turn it on expecting it to also have no Internet, no connection to the router, etc... just like before. But no! The moment I open IE, I'm on the Internet and all is fine! I can connect to the router, ping it, everything. "Huh?". So I go back to the laptop and it also is fine.

I chalk that up to a temporary weirdness and forget about it. But then it happens twice more last night and again is the case this morning. Now the "fix" is simply to turn on my wired pc. WTH?!?!

So really exact same symptoms as before, but its only affecting the wireless (all wireless, I checked multiple devices), and a router reboot is no longer necessary... just a "wake up" from the wired pc.

I really don't get it.

Nothing on the network changed other than the cable guy replacing the cable run and making sure the physical connections were all good.



I guess I'm either back to "its the modem" or the Gods are all against me and I have two faulty Asus routers and a faulty old Linksys.

- Steven

 

[coxhaus]

This sounds like inactivity is causing a drop off. Is there a keep alive function on the WAN router port? Can you figure out if this happens after a certain amount of elapsed time or inactivity? You then need a job to send a small amount of data across the internet after the time interval. If the job fixes this then you have solved your problem.
This is a problem with PPOE clients. I know you are cable but I believe it is possible to have this issue. I have only seen keep alive functions on PPOE interfaces on routers. I just thought I would ask.
My logs on my router pick up DHCP requests every few minutes on Time Warner which I believe they may use as a kind of keep alive function.

 

[Fraoch]

I just solved a similar wireless issue with the Intel 5300 integrated into my laptop. It would work flawlessly, then suddenly...it would indicate that it was connected, would still have an IP, but it was completely frozen. No wireless network access at all. This would happen after a period of inactivity, sometimes as little as 30 seconds.

Another symptom - I could not pull up the tray application to check to see anything about the network. It wouldn't do anything.

I downloaded "Intel PROSet/Wireless" which is a more advanced connection tool for the wireless card and provides access to all the card's settings. The last setting tab contained an entry for "allow this computer to turn off this device to save power". I unchecked this and haven't had a problem since.

 

[BCSteve]

Thanks coxhaus, but its not inactivity. It happens right in the middle of using the laptop or other wireless devices... and it happens on the wireless device(s) even while the wired pc is in the middle of using the Internet. Rebooting either the router or the wired PC seems to resolve it (this is new since the re-cabling... before that, the wired pc wouldn't work either).

 

[BCSteve]

Fraoch... if it had something to do with the laptop's drivers, then it wouldn't a) have been a problem on the wired pc or b) be a continuing problem with other wireless devices (kindles, xbox, etc)

 

[coxhaus]

Sounds like it might be a router issue. Does it happen the same way with the other router.

 

[BCSteve]

Same as I described before. Identical symptom except with the Linksys it doesn't show as there being a valid wireless connection. With the Asus it does. But in both cases, there really isn't any connection.

 

[coxhaus]

I think you should turn on logging in the router at the level so you can see DHCP requests for the WAN port and starting pin pointing the drop times. Maybe there will be something in the messages.

 

[tipstir]

On the WiFi devices like the laptop have you cleared out the WiFi management.

Those that remember your SSID info. You should really only have the one you use daily unless you travel. There are two sources. Also you can change the priority of the TCP/IP clients used.

But again WiFi LAN okay but WiFi WAN is not connecting what does the router logs show. To me best get a WiFi Router that doesn't give you internet disconnections.

 

[wh7qq]

My guess is that you'll go out and buy a new router...hardly matters which one...and still have your problem.

First thing is to check to be sure you are using the correct power supply brick for each router. Easy to get them mixed up.

Something I haven't seen in your comments is doing a hard reset on your routers to get back to factory default settings. You may have something in your router nvram that is the result of some setting that you input in common with all the routers. On the linksys, it is a 30-30-30 reset (hold reset button continuously through 30 seconds, then pull the power plug, still holding 30 sec., then still holding reset power on again, releasing the reset after the 30 sec. is elapsed) The Asus may have different methods to get back to factory defaults so check their information or this forum for how to reset the nvram.

Another cheap thing to try is to download one of the live linux disks and use it to sort out your problem. Most of them will wake up with the wired lan already working...regardless of router type. Wireless may be more complex. Knoppix, Ubuntu, Mint come to mind and all boot up and make a wired connection on their own. That will rule out a windows set-up issue. Windows can be very weird that way. Start with a direct PC-modem connection, then add the router, wired mode, and reboot.