Router, modem or both?

For the last 3 or 4 days I've been having intermtant lose of connection problems. Not just to SL but to anything that requires access to the internet. Two PC's connected via a router to a cable connection have the problem at the same time so I've narrowed down the source of the problem to one of two devices........the router or the modem.

Here's the symtoms. At irregular time intervals I will loose the connection to the internet. I check my LAN and it says "local only". That's a very good indication the resetting the router and/or modem is in order.......which I do and it fixes the problem (until the next time which could be a day or maybe an hour or so).

Now, my observations trying to determine which device is at fault. At first I reset both the router and modem at the same time....but doing that does not narrow down the device that is acting up. So, I reset only one at a time.....first the router since my network showed "local access only" and did not show the other computer on this network. That worked. Then, just to test further, on the next lose of connection I reset the modem only......damned if that did not work too. Okay, back to square one.

I called my ISP to get them to ping my modem from their end. The got a successful return. So I checked my LAN again and I had access to the internet......I had not reset the router or modem yet. Thanked the technician for their efforts and hung up thinking to myself what the heck did that prove?

So, next step (which was a little earlier this morning) was to open my network and map the whole network to see if I could see the modem when I next lost connection. I couldn't at first but by refreshing I could. I did nothing else to get my connection back.

Then, just a few minutes ago I lost the connection again. I waited it out. About 10 mins later I got my connection back without doing a thing except occassionaly checking my email to see if I could connect.

I know one of the devices are at fault. My best guess is the router but with all the stuff I've tried in order to confirm that points back to either of the two. It's not that is such a huge problem but more curiosity as to why resetting the modem would "fix" a problem with the router (or vise versa). Or recieving a ping from my ISP would get me my connection back. Or mapping my network seeing no gateway then refreshing that map and seeing it the next time. Or just waiting it all out and it "fixing" itself. I'm confused.

My router.....Linksyst WRT54GS
My Modem...Linksyst BEFCMU10

I'm hardwired with CAT 5e and the furthest computer (this one) is about 30 feet.......the pre made CAT 5 cable is 50 foot length.

Anyone have any suggestions on how to maybe determine which device needs replacing or updated? I'm out of ideas. I really don't want to replace both when I'm pretty sure it's only one that is at fault. And, being the tightwad I am, I don't want to replace the one I think is the culprit only to find my guess was wrong.

Thanks.

It is best to think of the router and modem as general purpose computers (which they mostly are) and are subject to all the weirdness that you come to expect from desktop machines. Alas, we like to think of them as toasters but they are software based and have bugs; the hardware can also act weird.

There is one device that you haven't noted and that is the network equipment port at your ISP's central office over which you have little control or visibility of - which can also fail in odd ways.

The biggest problem is that it is intermittent. Learn what all the indicator lights on your modem and router mean and compare them during normal operation and during failure.

Very counter-intuitive things can happen to any of the three devices when hardware changes. For example, unplugging your modem can cause the device at the central office to reset when it sees loss of carrier. How would you ever know?

Another useful avenue may be to talk to the modem itself. Many have a "technician" access usually through some obscure address; you might get your ISP to wink-wink let you know it. My modem has a web server at 192.168.100.1 (which shouldn't be a valid address). There is a goodly amount of information there including timestamped logs of various resets and loss of signal. You could get involved in packet tracing but even that bombs with flaky hardware. The next step would be swapping out devices with a friend. Finally, you can also call the ISP and with an air of great authority declare that their port is bad and you should be put on a different one.

Hope this helps your diagnosis.

That sounds like what I had last year-I lost synch with my DSL signal every few minutes, which got me kicked out of SL, of course. I didn't notice it so much with other applications that didn't need a constant connection. It turned out to be my ISP's fault but they never told me what the actual problem was. I spent days trying to find out which of my devices could be the cause. You should really check the connection logs if you actually lose synch (and thus the connection)-so if you see a reconnect every few minutes my guess would be it's the line.

With the sales pressure being put on ISP's these days, with such high competition, many will try and sell you greater and greater bandwidth speeds. This is mainly acheived by 'interleaving', which in laymans terms means, stacking nodes. A node can support X users with a capacity of say 2mb, therefore 2mb / users = contention ratio, usually around 50:1 for domestic connections, 20:1 for commercial.
To sell you the concept of more bandwidth speed, they stack (interleave) the nodes. 10 nodes @ 2mb = 20mb connection speed... but now the contention ratios have also been part of that equation, which for a 20mb connection has risen to 500:1.

As the nodes become overloaded by the connections, they rely on caches to store your precious packets, which has a lifespan. When their time is up, they are disguarded and you have to resend them. Should latency get too low, your pings are ignored by the node and you loose connection.

Get back onto your ISP provider and badger them. I used Dan Elwells excellent programme (Speed test 32) that takes a series of tests, which I could send the results direct to my ISP support email address. They got fed up with the emails and sorted out my line. You are allowed to send up to 10 email reports per hour, without it being considered spam.

One last thing, a 50 foot Cat5 cable is okay for boosted router networks. I would suggest moving the modem closer to the computers, as a telephone line is powered, and keeping the Cat5 to less than 10 feet.

You may be on to something AVM. My ISP has just recently offered more bandwidth (at an additional charge, of course ) up to 20 mbps.........I have 6 mbps now, which is quite adequate for me.

Though I've not lost the connection much since starting this thread it has happened a few times. So far I've just waited it out anywhere from a couple minutes to maybe 15 minutes. Somehow, if it were a router/modem problem it does not make sense to me that it would "clear" itself with no action taken to reset.

Thanks, I'll check out that link you gave.

From a sales angle, the ISP's will interleave you anyway, just not allow you to share in the greater bandwidth, this doesn't always mean you dont share the contention ratios.... I got mine increased without the interleaving, the sqeaky wheel gets the oil first