Mysterious Internet Connection Problem

This isn’t really robotics related, but I figure asking here is as good (if not better) than asking elsewhere. I can not explain why the modem at the local food pantry keeps dropping the internet connection. I can not get the thing to stay connected to the internet. It is a SpeedStream 4100 (dsl). I brought it home to test it. It is what I am using right now with no problems. As soon as I take it there, it will not connect to the internet. The cables have been replaced back to the phone and the router (a dynex) taken out, but the connection will not stay up. It finally just quit one day and I called the phone company. They said they would come. A few months later(I couldn’t make it back until today), the connection is still down. The phone company never came, and several other network quru’s could not solve the problem. I am at a loss. Someone installed a new DSL filter right before this. It seemed to work, but could it be the problem? If anyone else has an idea about this problem, please let me know.

DSL is a tricky thing, the phone company should be able to test the line and see if it returns any errors like ground faults, imbalances or high impedance or high shunt capacitance. Have they switched you to a different trunk that now routes you over to the other side of town and exceeding the max DSL distance? If they did some rerouting, they may have also failed to remove the previous wiring which looks like a shorted stub to DSL signals. They should be able to perform those tests while they are on the phone or certainly within a few minutes. At your end there may be a loose wire or a wire sitting in some water. Do you have a phone connected to this line? How does it sound? Pick up the phone and dial one number and listen when the dial tone is gone. You should hear very little noise, hum or other conversations. If you do, there is something wrong with the line between you and the central office. Does the modem try to acquire the line? Is it going through the normal boot sequence when you first power on? Did someone install a wireless phone or other RF generating device? Some modems are sensitive to this although I have a wireless phone and my ham shack in the same room as the modem with no problems. Depending on your provider they may be using a local vendor for connection services. I had Earthlink who used Covad locally for connection to the phone hardware. If this is the case, see if you can get in contact with the vendor engineering people and see if anything new equipment has been installed and if it was installed about the same time as your failure. Have you tried taking your modem to the failure point to double check? Were you using the same power supply when you checked at home?

By filter, do you mean the one that goes to the phone line to the phone?

If so, you might want to check that it is going to the PHONE and in the right direction.

Also, it would GREATLY help if you explained how/if the phone is working. You did not make it clear as to whether that even worked, but as of now, i would assume the phone is working fine, as you did not mention it.

phone works perfect. I actually had to work on the phone line a few weeks before the problems started. There was a connection in water that was shorting. I fixed it and it is no longer in the water. After that, someone else (I wish the boss would mention it when she has other people work on this stuff. They always seem to mess up the system I set up and I have to repair it) I beieve was a former AT&T employee rewired the office so that 5 splitters were no longer needed. He installed a new DSL line filter that is completely enternal. You take the lid off, screw the wires in, and put the cover back on. Also, AT&T ran the tests. It works fine from their end. I did not do anything different to the modem. Same power just a different line at my house. The pantry is under a plaza, so radio waves are not an issue. No towers and shielding from the thick concrete wall next to it. Right before the connection died totally, the modem stopped taking an access code from me. Now there are no problems. That is why I suspected the modem originally.

Hmmm… Im not really specialized in this.

Has it worked at all since the AT&T rewiring, and the filter installed?
Can you communicate from the PC to modem at the pantry?
Does the modem itself seem to respond to the internet(correct lights on)?

Just to clarify… the device I know of as a DSL line filter is designed to block out the DSL signals from the phone line, so that you can use a regular phone and not hear the humming, clicking, beeping, etc that [Al] was referring to. However, since it blocks out the DSL signal, the modem won’t work if it’s connected to a line that is being filtered.

So…I think [Stormnnormn] already referred to this, but the stupid question is, do you have the DSL modem hooked to a line that has a filter on it?


Incoming line-------+---Filter-----Phone


Incoming line-------+---Filter-----Phone


I am not sure. I think it worked for a few days after it was rewired. I can communicate to the router from its ethernet port from every computer I have tried it with. Router or no.

Maybe I was wrong about this. I thought there were 2 filters. I thought 1 filtered out DSL signals from the phone line, and that one filtered out phone signals for the modem. I could be wrong (please correct me if that is the case). Anyway, the box is marked as DSL out or phone out and the wiring is correct as far as I can tell.

Are you connecting the modem the same at both locations? IE is there a router the modem is connected to at both test locations?

If there was a router atached at your house and it works, the modem would be in bridge mode (the login credentials are entered in the router), and if there is no router at the pantry than the modem needs to be set in normal mode(login credentials are entered in the modem).

Try connecting the modem at the pantry directly to the Demarcation piont, bypassign every phone line, etc in the building, if it connects than, that would indicate that the fault exist in the building, if not than the problem is upstream of the demarcation piont, and probally a problem with the providers network.

For reference in case it helps, there is a high-frequency signal for DSL and a low-frequency POTS (plain ol’ telephone signal) on the one line coming from AT&T. The filter separates the two with high- and low-pass filters so that each device only gets the signal frequency range it’s meant to. The filter should completely eliminate the possibility of the modem getting a POTS signal (the modem should have its own high-pass filter) or the phone getting the DSL signal.

Have you tried a different modem there? You can usually find them at Goodwill or such places. Might be worth a try. On the other hand, if you’ve got a DSL connection at home, you could try using your modem with the pantry’s setup just for a test.

A standard DSL/ Phone filter is used to separate the high frequency from the phone. To my understanding, the modem/computer is good enough at separating the digital freq. from the analog that it doesn’t need a filter. However, there may exist another filter I am not aware of.

At my home, I have (A)DSL. I have the same modem, but an older 5360 model. I have one cord going to the phone, with an obvious filter. The other cord goes directly to the modem —> router —> computer. (My home connection is working fine.)

However, since the filters were installed in the wall or in an outlet, the modem might be behind a filter. To my understanding, you were not the one that installed them, and were not really in the loop. Assuming you know where the filters are and what kind they are, then my idea really is not valid.

Ryan did a neat little diagram to show what I am proposing. Remember, a filter is designed to keep one thing out and let one thing through. Such, an air filter lets air through and traps the dirt. If somehow there is a filter blocking the DSL on the way to the modem, then there is the problem. If not, it is obviously something else, and that something is probably something I have not dealt with.

I will be thinking about this for the next few days if we don’t figure it out… I am like that. I have been thinking about getting into information science and networks. Always glad to help (or try)!

EDIT: I just re-read that you wired it into the dsl out/phone out correctly. So this may not be the problem. However, there is still the possibility of it being wired incorrectly so that you can’t see. However, there may be other things you could check before you pay somebody to rewire the phone lines in the building.

The modem has a small DHCP server on it. It works with or without a router. I have one at the pantry. It doesn’t matter. It works either way. It maybe difficult to hook it strait to the phone line. I can try a different phone port, but the connection may be difficult. The pantry is in the basement of an older strip mall. I am not sure, but I believe the box is on the roof. The phone line running out heads upward and I doubt the owner would be real happy if I start climbing on his building.

First off, thank you for being patient with me.
I am from Generation Y, and I get lost without diagrams, so here is one…
Tell me if it is correct… (Ignore the joke about the phone company)

First off, thanks for replying. That diagram looks correct. This is an ex restaurant also, so there are multiple phone ports. I will take my laptop and try a different phone port. If that works, I guess I will be rewiring an office tomorrow.

I don’t really want to suggest that, but I cannot stop you. If you havent already contacted the modem company, I would suggest that. Maybe something is wrong with the modem or they have experience with that.
Contact the modem company if you can, as I believe you have already contacted the phone company multiple times.

EDIT: I believe SIEMENS is the modem company, if that helps.

EDIT 2: I read that post wrong again, by all means, you can try out the other lines/outlets if it isn’t too much of a hassle. I still would not recommend rewiring it yourself, unless you know what you are doing.

I might take my home modem with me also just to see. The guy down the street works for AT&T and has several identical models in his garage the company was throwing away. I can probably get one if I need another.

I guess I was speaking from my personal experience; with my AT&T-supplied DSL in the Seattle area, we were given discrete filters to insert inline before POTS phones, but no filters for the modem. Now that I think about it, it makes sense that there would be a high-pass filter for the modem, so it’s probably built into the modem itself. I’m pretty sure that my modem is a different brand, however.

If you have the same service, this should (hopefully) work, but keep in mind that there are several types of DSL: xDSL, ADSL, etc.

Good luck,

It should be easy to bypass the installed DSL filter. Once that is done, you can use one of the individual filters and see if the modem connects. If it does, then you know the installed filter is hooked up wrong or non-functional. Perhaps a simple visual inspection of the filter will answer all your concerns. Make sure it is a DSL filter and not something else. External filters of the type you describe are just hardened versions of the same filters you were already using. Effectively they just keep the DSL signals from being attenuated by the phone internal electronics and keep the 90 volt ring signal out of the modem. I am guessing you are going to find a very obvious problem.
On the subject of the wire in the water. Many types of wire use a clay filler in the outside jacket which absorbs water. If the cable in question was a standard phone cable with 4 conductors and a grey jacket, then it is possible for that to suck water inside the jacket by capillary action. If the filter does’t fix the problem, then you might want to try eliminating that wire from the system.
One rule of thumb we use is called the Nottke Rule. Go where the last person was working and double check that the work was done correctly. Even experts make mistakes.

I am currently at the pantry. She had a second line installed a while ago. Someone put a fuse box inline and a DSL (low pass to cut DSL noise) filter on the box for one line. The last time I was here, this was not there. I went to a phone in the back and plugged the modem it. It works fine back here. I think someone routed the lines to the wrong places. The one with the filter went to the office with the modem. The one in the back has no filter so the modem works fine.

This could very well could be the problem. We all came up with the same problem, and explained it 10 different ways.

I am a little surprise there has not been any noise on the phone, but it doesnt necessarily have to have any. I have had our phone hooked up and no filter was there until somebody told me to move the phone, and I noticed it. I think the phones can handle the signals better nowadays.

Anyhow, I hope that solves your problem.

The filter was on the line going to the office. As soon as I removed it, the modem was able to connect. Now the router decided to die. I can not connect to the internet through it even with factory defaults. I am at a loss there. I can find no reason the router should be faulty.