When I was paying for their rental modems, I never had a problem which required modem replacement.

When I got sick of their 10.00/mo rental fee, and bought my own modem, it worked great for 5 months then stopped working. Purchase replacement, works fine, bricks about 5 months later.

Now it's been about 3 months and this third modem is on the fritz. I'm not sure if it's bricked yet but the circumstances are starting to point that way.

These are all modems on comcasts approved list. First two were arris tm822g, this third one is arris tg862g. In fact after provisioning the latest one I notice that comcast brand firmware got automatically installed on it. So I know that Comcast CAN do shit to the modems. The question is, do they? Are they really that much of an asshole?

Anyone know anyone who is deep internal at Comcast whom we could poke for information? Or maybe at Arris?

docsis means they do and always will push their firmware to it. that's basically what the approved list is for: firmware they can and do provide.

But the tm822g units didn't ever get any Comcast-branded firmware on them.

I suppose Comcast just chose to push arris-branded firmware onto them, perhaps they didn't have Comcast-customized versions of the tm822g firmware.

All three times though, the firmware still LOOKED fine from the admin page, it's just that the modem simply stops working, unable to register with Comcast on the cable line.

All US cable and Internet providers are assholes. Move to Europe.

when i had signal sync issues i reported them, leaving the modem up and reporting the mac, and a truck roll resulted in them stringing a new lead to my house from the pole (which i could practically reach out the window and touch). never recurred.

of course, we went fios and that doesn't have such issues.

I poked at it this morning and the downstream and upstream channels can get 1 channel synced fine. (Sometimes it looks like it can't because the modem keeps resetting the connection as part of its self-healing and so sometimes I look at the connection page and it's in the process of resetting.) So I think the cable line itself is fine.

When the channels are connected and synced, the modem's status page shows it getting through all of the connection stages except the last one: "Registration".

The Comcast-branded firmware that's loaded onto this modem isn't keeping logfiles and I can't find an option to turn that on. So I can't see the detailed reason why this modem suddenly stopped being able to register with the service provider. But at this point it looks like it's not actually a problem with the modem, it looks like maybe it's a problem with Comcast de-registering my modem's CMAC. Classy.

When I called them last night, they said they'd send out a technician (and then there was the problem that it's mid-week and I work a 9-5er and they don't have any pre-9 or after-5 slots this week) so I might have to wait til saturday for this to get fixed. However, I'm going to try to poke them on the phone and see if they can fix my CMAC.

And their web site lists my cmac as correct. Hm.

I had a long series of issues with Comcast - recently resolved (I hope). I'd had no trouble for years before they "upgraded" my neighborhood in preparation to increase max speeds.

I had a series of outages thereafter, every few weeks. They replaced my modem. Replaced the cable from the street to my splitter. Replaced my splitter three different times with different resistors. Replaced every single connector. Each time it would work for a while, then go intermittent, then go out.

I took to keeping a log of screen shots of the signal strength page from the modem, twice a day - morning and evening; the signal would degrade some time after a visit, became borderline, then wouldn't hold.

Finally, a "senior" tech came out - turns out that they were doing stuff in the neighborhood subsequent to the "upgrade" and throwing my house back out of tune. They seem to have stopped playing in the neighborhood, or at least within very small adjustments. Throughout all of this, I never had TV issues.

-jk

You mean the company that regularly changes the names of their own customers to profanity on their billing statements?

Hadn't heard about that one. Looked it up. That's interesting.

Knowing that they can do that kind of shit in their system, and that the employees are unmonitored to enough of a degree to allow that kind of thing to happen, means that it's not farfetched to suspect that someone in the company is deliberately fucking with me.

I've had great luck with cheap Motorola SB6141's. Rock solid. but that was with Time Warner.

My older SB6130 also was very stable on Cox, Time Warner, and Comcast. Tony, if you want to borrow it for troubleshooting purposes, let me know. Been sitting collecting dust since it was replaced with a VDSL2 modem.

All of my contacts there went underground once word got around that Comcast was the lead contractor in the faked moon landings. Trust no one.

Okay I think I see the bit that got fucked up, the WAN MAC address is borked. It's mostly zeroes when it should be just one digit off from the cmac.

No way to fix it. I'm convinced it was Comcast that altered it.

One digit off? Surely the WAN MAC address is the CMAC?

Peter

i've never seen the customer provided equipment mac be called the WAN mac, and it shouldn't cause issues with their system regardless, only yours.

I'm not talking about the local ethernet MAC, I'm talking about the MAC Address that the modem presents to the cable line. On the cable interface. Look, here is what I'm talking about specifically. Attached are two photos. One of these is the label printed on the modem itself, and the other is a screen shot of the modem's status page.

If the WAN MAC address is screwed up, the modem won't work on the network. And it's been screwed up. I believe that Comcast has the ability to brick a modem by remotely altering these kinds of values.

This particular modem I think it took them several tries. The modem has been rebooting itself every once in a while and losing all its configurations settings each time. I think in the few months I've owned it, it's rebooted itself maybe four times, intemittently. I think those reboots were all attempts to fuck with its configuration.

How do you get to the modem webUI?

the googles found it for me

If you can't set a tough password, so that Comcast can still do it can't some random hacker do it, too?

-jk

What does the manufacturer say about such things?

Comcast, or some random hacker taking advantage of the lack of WAN security on many such products?

I am beginning a dialogue with Arris, and they say that the WAN mac address should be unchangeable, they are as surprised as I was to see that it was different. We'll see if they are able to escalate this into something that can get me some resolution here beyond "buy yet another new modem and keep doing it as long as this problem keeps resurfacing".

Certainly within the realm of possibility. But if a hacker can change it, surely then Comcast can change it back? Hopefully tomorrow's tech visit will be a repair rather than a "sorry dude you gotta get a new modem" again.

Or perhaps a friendly hacker can change it back

If this problem is widespread, perhaps there is an opportunity for someone to offer a fix?

I saw a page about using an SNMP tool to access the Arris modem in "Technician" mode, but it said that it no longer worked with the updated firmware. That's the thing: I think these modems do have backdoors into which the technicians can poke, but pretty much only Comcast knows them at this point.

Tell TimeWarner, AT&T, Verizon, Charter and Cox that you'll switch if they can un-brick your modem

If back doors exist, it seems likely that people outside of Comcast (or formerly of Comcast) also know about them. Whether those people are using that knowledge for good or not good is a separate question.

@John, your assuming one of them also services his area. In my neighborhood, which I believe is similar across the US, it is Comcast or 3mbit DSL from AT&T, oh and satellite. Oh how I miss Verizon FiOS

Indeed, in my neighborhood in seattle, comcast is the only available service. When I moved in, I couldn't even have gotten qwest DSL if id wanted it. That may have changed recently but I'm still pretty sure it's either qwest DSL or Comcast cable round here. There were some experimental fiber rollouts to some neighborhoods but they never reached mine.

Final answer to this mystery:

Known bug in the Arris firmware. The issue is that there's something wrong with the DHCP negotiation in the final stage of registration. The problem is permanent, and can't be fixed without just replacing the modem.

By "known bug", I mean, it was a bug that's been occurring for years now and only recently (last 6 months) did the comcast techs finally understand it to be an actual bug that made them keep having to replace Arris modems. Supposedly, according to my tech, Arris has acknowledged this bug. Now, since Comcast supplies the firmware, I don't see why they can't fix the bug and push out a new firmware rev, but I don't understand how this stuff works on the back end.

Turns out it's the same bug on TM822G and TG862G models. My problem is that my selection of available models is very narrow due to my VOIP land line requirement, so I don't have a lot of choice in this area. On amazon, there are very few VOIP capable cable modems that I can get which are fulfilled by Amazon (I've had trouble with buying items from "amazon sellers" for orders which aren't "fulfilled by amazon", so I try to avoid those). So when I had decided that I wanted to order from amazon and get the modem overnighted, I was left with, like, two models that were on the comcast approved list. So if the bug was in a narrow range of models, and I was stuck buying models in that range, it's no wonder that it looked like an unusual coincidence that the made it look more like malice than bug.

I've ordered, from a less-reputable seller, a different VOIP model from SMC in hopes that it won't have the same bug. Only other kind I could locate.