[SOLVED] SOLVED: Losing Internet Connection

[dachay2tnr]

I have a bit of an odd one. I have internet and telephony through my cable company. About three weeks ago I returned their modem and installed my own. Same make/model as theirs, just tired of paying the rental fees. Everything ran fine for about two weeks. Then last Saturday my internet (and telephone) went out. I rebooted the modem several times, but could not get it to fully boot. The following day I attempted to swap the modem for a different one. The new one also would not fully boot. So I decided to put the first one back and call my cable company. However, when I put the first one back, it rebooted and all was fine again. Until...

The next day it went out again, and would not reboot. I decided to swap the coax cable coming from the wall to the modem. As soon as I changed the cable, the modem rebooted and all was fine again. Until...

About 24 hours later the cable went out again, and the modem would not reboot. This time I decided to try and relocate the modem and router. I moved everything to another room, and the modem immediately rebooted. And everything was fine again. Until...

You got it. After another 24 hours the cable went out again, and I could not reboot the modem. I moved everything back to its original location, and the modem rebooted fine and I have internet again. That was about 14 hours ago, and if history repeats, I will likely lose internet again tonight.

I am completely baffled by this. I cannot imagine why changing cables or moving the modem would provide an immediate but temporary fix to the problem. The only other possibility I can think of is the amount of time the modem is unpowered. Normally when I attempt a reboot I pull the power cord out for 10-15 seconds and plug it back it. Those are the times when it won't reboot. When I change cables or move everything, the modem is without power for a couple of minutes. Not sure why that would make any difference, but I'm grasping at straws. If it does go out again tonight, I will try powering down for a longer time (without disconnecting any of the other cables) and see what that does.

Other than that, I cannot figure out what would cause this behavior. Everything runs fine for 24 hours or so, and then suddenly it doesn't.

 

[alceryes]

Are you doing all your testing connected directly to the modem or are you going through a router?
Have you notified your cable company that you got a new modem? Given them the Mac address? That's usually not needed but it's worth a shot. You could also try purchasing another modem (from somewhere that has a good return policy) to test.

 

[dachay2tnr]

Thanks for the response. I “think” I have this solved.

For what it’s worth, everytime the system goes down I am able to get it back by disconnecting the coax cable from the modem, and then reconnecting. That’s why all of the above attempts seemed to fix the problem. Each one (new cable, relocate modem, etc.) required disconnecting the coax cable. A simple reboot, though, does nothing.

Anyway, I checked the modem status page and found my upstream power levels are running around 53-54 dBmV. From what I gather, this is pretty high, and if they go over 55 or so, the modem will cycle itself. Given the signal level is running close to the edge, I’m guessing occasional fluctuations cause it to go too high and that’s when I get the dropouts. It also explains why they’re random.

One fix might be to eliminate the number of splitters on the line. After coming into the house, the cable is split 3 times before it gets to the modem. Or maybe to move the equipment to a location where there are fewer splits before the modem connection. Unfortuately, Because it’s a telephony modem, I’d need a location where there is power, coax, and a phone jack. None exist now, and rather than running new wire, I’m going to try an amplifier. Apparently ones that feature an active return will boost the upstream signal.

I’ve ordered it, and I’ll check back in once it’s in and installed. I’m pretty comfortable thst this is the issue and fix. Fingers crossed.

 

[bill001g]

I would take the modem and connect it to the connection as it enters the house not so much to use it but to get the number. If this number is already close to 50 I would see if the ISP can check the cables in the street and see if they can improve it. I did not have problems but my neighbor had issues. Seems the spliter they were using out in the street that provided both our houses was having issues. Seems water got in the connection going to their house because they forgot to put the rubber washer in that makes it water tight.

 

[dachay2tnr]

Thanks for the reply. I moved the modem and router to another bedroom. This bedroom has two splitters before the outlet, whereas where it was located before had three splitters in the line. This move caused my downstream levels to increase to about 6 dBmV. Not as good as they were previously, but still within spec, I believe.

The upstream levels dropped from 54-ish to around 51. Still high, but better. However, before I was getting tons of “correcteds and uncorrectables” and now I’m getting essentially none!

So far it’s been pretty solid, but it’s only been a few hours. I’ll post back later to confirm this did the trick.

 

[dachay2tnr]

Here’s an update for anyone having similar issues.

After moving my equipment as described above, the internet has been up and running for about 26 hours now. I’ve managed to do this before the move, so it’s not definitive. However, just prior to moving the equiment it was dropping out every few hours. So I’m optimistic it’ll continue to stay online.

However, in querying the modem I am now seeing errors - both corrected and uncorrected. My guess is that this is due to my upstream signal level still being on the high side.

My plan going forward is to purchase a return path amplifier, move my equipment back to it’s original location, and install the amp on the coax line feeding the modem. If it goes as expected, that should put my downstream signal at around -2 to 0 (where it was before), and lower my upstream signal to the low 40s.

 

[dachay2tnr]

Here's another update.

As mentioned, I had moved my modem and router to another location where the upstream levels were still high, but slightly lower than in the first location. Things seemed to be better there, but after about 48 hours I did end up getting dropped internet connections there as well. So while improved, moving everything permanently is not a fix.

Moving on, the return path amp I ordered arrived this afternoon. It has been installed and it did what I had expected to my levels. Downstream levels now range from about -3 to +1, with SNR ranging from 38.6 to 40.3. Upstream levels are now between 37.25 to 43.25. From everything I gather this is pretty much exactly where they are supposed to be.

The proof, of course, will be if it remains online without dropping the connection. We'll see how that goes. In the interim, I have two issues bothering me. I am still seeing both corrected and uncorrected errors. I was hoping they would go to zero with the lower upstream levels. At this point, they are few (and only on one DCID for the uncorrectables). So I don't know how much of a concern that should be. But that's only with about an hour of uptime. Additionally, my upload speeds have dropped. I am getting around 115 mbps download speed, which is what I pay for and what I have always got previously. However, my download speed is now around 10 mbps. Not sure what I pay for, but it has always tested around 30 mbps in the past.

I really don't upload much of anything. So I don't care particularly that it's only 10. But I don't understand why the return path amp would lower the speed. (I'm assuming, of course, that this is due to the amp - since nothing else has been changed.)

 

[dachay2tnr]

No cigar. Even though i am getting decent signal levels now, the internet drops continue.

This morning I went to my cable company store and got a modem. Hooked it up without using the return path amp. Upstream levels were 53 dBmV on all 4 channels. And within an hour or so, I got another internet drop. So at least that pretty much rules out a bad modem.

I just reconnected using the reverse path amp. Upstream levels are down to 38.5 - 43.75. So far it’s been up and running for about 1-1/2 hours, but I’m not expecting any changes. Have a service appt scheduled with cableco for tomorrow. Hopefully they can figure it out.

 

[bill001g]

I would try to force the ISP to deliver less than a 50 upstream power to your house. Better if they could get it into the mid 40's. This leave you a little room to work with. You really should not need to use amplifiers.

Your modem should have a log. Generally you get a lot of messages when it is a signaling issue. Most these are sent to the ISP also.

 

[dachay2tnr]

Thanks, bill001g. Had the ISP here today. He tested the signal coming into the house. Never looked at the modem, or any other connections - although he did read the modem logs and status remotely.

Long and the short, he doesn’t know what the issue is. Agreed upstream signal is on the high side, but said it’s still within their spec. He also said not to use an amp. Obvious reason it raises the noise level (and I can’t read the upstream SNR to even see what it is). Anyway, I’ve removed it from the equation as it didn’t solve anything.

I could bring the modem down to my living room. The connection there has only one splitter upstream of it. The location isn’t really convenient for me though. And I’d have to remove the coax from my TV to attach to the modem. So I’d lose cable tv (unless I add a splitter, which kinda defeats the purpose). That’s not a disaster as 99% of the TV I watch is from the internet (Netflix, Amazon, Playstation Vue, etc.).

In the meantime the ISP tech is supposed to escalate the issue within his organization. So
I probably won’t do anything further until I hear from them. At least to this point they seem to agree it’s their problem - although I’m the one with the consequences.

 

[dachay2tnr]

Cable company just ran a new line to my house from the junction box. Not sure if they felt there was a problem, or they’re just ruling out possibilities.

I checked my signal levels. Downstream levels are a couple db higher. Upstream levels look to be unchanged. So....

Time will tell, I guess.

 

[dachay2tnr]

This is turning into a book - hopefully not a trilogy.

The new cable line did not fix the issue. So my latest approach was to move all the equipment to a 4th location. This location is directly off the first line split coming into the house. The upstream signal levels are much better here. 46-47 dBmV. They were 51-54 everywhere else I tried. But (there’s always a but), my downstream signal levels appear to be way too high. 13.1 - 14.8. I’ve read conflicting info on this. Some places say -15 to +15 is acceptable, others say -7 to +7.

Anyway, the two changes I’ve noticed here is my error levels are way down. This is only after two hours mind you, but I have 0 uncorrectables, and 7 or fewer correcteds on just 3 of 16 channels - the rest are 0.

The other thing I see is the spread in signal level is tighter. Previously the difference from low to high on the ds channels was about 4dB. Now it’s under 2.

Whether any of this means anything remains to be seen.

 

[bill001g]

A though not the optimum solution sometime what you can do is use MoCA to use the coax cable to extend you network back to the location you had it. I have never tried it between a modem and a router but it should work. Be better to place the modem and router at the entrance location and then use moca to extend the network back and put a AP in the remote location for wifi.

If you really thing the high levels are going to hurt you can get attenuators that cut only the signal levels used for downstream. Most times the upstream are well under 200mhz and the downstream are well above so a filter that degraded only signals above 200mhz would be cut those levels.

I bet all your problems were the upstream. You 50 numbers were near the upper limit you are now well withing the recommended values. Maybe you get lucky and it will work now.

 

[dachay2tnr]

Thanks again. Not sure what MoCa is, but my Wifi coverage is fine in all locations. The house is relatively small, and I can pretty much connect from anywhere, regardless of where the router is located.

The main issues with location are cosmetic, and the ability to connect my desktop via ethernet. But if I have to pick up a wifi adapter for the desktop, so be it. Small tradeoff for the ability to remain online.

The forward path attenuator is an interesting approach, and one I might use if it comes down to it. However, despite the high ds signal level, everything has been fine so far (11 hours and counting). At this point I still have zero uncorrectables, and a smattering of correcteds - none higher than 22. So things are looking good. Fingers crossed.

I’ve been able to run longer than 10 hours before. So I’m not closing the book on this. But ten hours with zero uncorrectables is heartening.

The high ds signal levels only concern me if they result in some issue. As long as things run ok, I don’t really care what the levels are. As they say, don’t fix what ain’t broken.

 

[dachay2tnr]

I guess I’m gonna call this one solved. My internet has been up and running for over 3 days without a crash. Error counts are way down. Modem log shows 5 events. Three are lease renewals, which seems to happen every day. The other two are T3 timeouts - “No Ranging Response received.” None of them have knocked me offline.

For those who do not wish to read the entire thread, here is a short summary:
About three weeks ago (two weeks after installing my own modem in place of the ISP’s) I started getting random internet drops. Looking at the modem admin stats, it appeared that the upstream signals were too high (~54 dBmV). The downstream signals and SNR were fine. Swapping cables, replacing splitters, switching modems, had no effect. Same problem. ISP even ran a new line to the house - still no change.

Finally moved the modem and router to a new location with just one splitter upstream (previous locations I tried had either 2 or 3 splitters in the line). Upstream signal levels dropped to about 47 dBmV. However downstream levels jumped to around 14 to 15. SNR stayed fine, or maybe improved slightly. Regardless, it has been able to stay online under those conditions, and there are significantly less FEC’s.

Fingers crossed.