Is Xfinity or Arris responsible for upstream power levels

Thanks for the confirmation that I was not alone. It got worse a few weeks after I first posted. Like you, I started to have to recycle the power every few days. And no one takes responsibility for why that was. I finally gave up and rented an XB7. Been a few weeks and getting my consistent 940 downloads and not one power recycle required yet. So all is well...except for having to rent and wasting money on a modem because no one really explains that if you buy one you roll the dice and are on your own if you have issues.

I have the same problem.

I spent most of the morning going through the troubleshooting routines with Comcast only to be told that they CANNOT see the power levels in the very telephony modem COMCAST recommends.

CSR send the magical "signal" to the modem, takes 10 minutes to reboot, and nothing changed.  As has been the case 25 times before. CSR tells me she sees green; however there are still thousands of uncorrectable errors -- which can be heard as static on audio and seen as pixelation.

So, I call Arris, and they have no trouble at all getting into the modem and telling me that the singal levels on the UPSTREAM side are bad.  Should be 45-51; highest one I have is 31.

Downstream should be -15 to + 15, so she said they are fine, but that the errors should not be appearing, especially uncorrectable. 

Arris CSR tells me that only Comcast can make the signal level adjustments, that NO tech needs to visit the property, and that they should be able to see the signal levels just as easily as Assis CSR did.

Here's my data for the last hour (I reset the FEC numbers an hour ago).

There is only one splitter between the cable modem and incoming line; new short Comcast-supplied coax line from Comcast between CM and wall outlet.

No problems with previoius Motorola MB8600 at same property with same lines, splitter and cables. 

How do we get someone at the Comcast headend to fix the signals?

Status

Similar problem here. I'm not convinced that the signal levels have much to do with the modem "crashing" -- the signal levels are basically the same all the time and the modem seems to be having a problem recovering from a line glitch or something. Signal levels might contribute to a higher error rate though.

Interesting that the Arris web page showing the required signal levels shows an example of upstream levels that are outside their specifications. I'm not convinced Arris really knows what the signal levels should be.

Comcast really needs to stop recommending the T25.

You may be right.

Between, Comcast, Arris, those who comment and support here, Comcast phone agents, site visiting techs, and "2nd level escalation" agents, no one can seem to agree or explain exactly what the "signal level" is, who or what controls it, how it changes or adapts, how and by whom it is measured, and why Comcast cannot see any of these signal levels on it's recommended / certified T25 modem.  I don't think I have seen two consistent answers among all of them. 

I am traveling now, but I plan on escalating this to my coumty's cable regulation office when I return. They have direct access to "executive" decision makers in an office near Baltimore who can cut through the nonesese and get things done. 

Either stop recommending the T25 or collaborate with Arris to fix the problem......

Arris grumpily replaced my T25, but was confident replacing it wouldn't solve my problem.  The new one is still unopened because I feel like I'm wasting my time trying to make it work.

  Funny, but not funny. I'm glad to see my thread is still generating interest.  But I may have hurt myself by starting it.  Put the T25 modem on Craigslist for $80 and only one nibble after 3 weeks and he contacted me a day later and changed his mind. "After doing more research have decided to go with another product ". Probably read this thread.

  On the bright side cannot be more impressed with the XB7 after six weeks. 940 download everytime. Not one reboot yet. Just why can't I do that with a purchased modem?

There was mention in another discussion thread that Comcast is expected to deploy a firmware update by the end of the year addressing this issue.

Meanwhile, I tried moving to a Motorola MT7711, which is a router, and running it in bridge mode. It turns out that even though the MT7711 is capable of operating in bridge mode, Xfinity forces it into routing mode. That would mean I can't use VPN or IPv6 features of my router, so I returned it and I'm back on the T25.

I want to jump on this bandwagon. My Arris T25 locks up every couple of weeks and seems to do it only at night. Like everyone else, I am told that Upstream QAM power should be min 45 max 51 - and my 24-31 dBmV are below the minimum power levels prescribed by Arris. 

A call to Comcast yielded them resetting my gateway. My speeds are great (950+ D/L and 40+U/L) and gateway performs great. 

This is just crazy. I hate getting up on a random morning just to reboot the silly gateway.

Has anyone resolved this issue other than getting a different device?  

Hi,

Just a general response. When Comcast makes a statement about a specification, keep in mind one question - what's your source?

Specs aren't pulled out of thin air. They need to provide you with a technical source for that specification. Like them telling you that power levels are fine. Ok, so what's your source for that spec? Don't tell them they're wrong because your source says this, but rather make then state their source.

So make sure that whenever you have to deal with any technical support, and you have what you believe to be a realible source for technical information which contains a specification that points to what could be the cause of a problem, you should always make sure that you have information on the source for the spec. Something official, like the 802.11ac specification on bandwidth is this many MB's per second.

Good luck,

Dave

This thread has run its course. Six month old thread now being closed.