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.

Is this something that a separate VOIP box could not provide?

I use an Obihai OBi202 for my own VOIP, with separate router (Apple) and separate cable modem (running in bridge mode).

Not sure if it's possible to do a separate VOIP box with Comcast, but I think my real endgame here should be figuring out a way to do away with the land line entirely. Primarily we need the land line to support the alarm system, but there's a such thing as alarms that work with cellular technology now, so we could theoretically switch to that.

You should also be able to get an GSM gateway(?) where you connect the phone cable from your existing alarm system to the land line port of the box and it will use the GSM network to route the alarm calls. That's what I did with the alarm system in my previous house.

Yeah... maybe it is time to say good-bye to the Comcast VoIP line...

Glad to see you found the problem.

If this is just for outbound calls from the alarm system, a separate VOIP box would be very inexpensive. I use VOIP.MS which is prepaid. Even using their premium tier outbound service the cost is one cent per minute. The only monthly cost is for inbound phone numbers ($1 per month), which you may not even need.

A $25 prepaid account would last a long, long time in such a configuration. Obihai makes several boxes. I prefer the OBi202 as it is fully featured. Configuration is a bit technical but once set up it just sits there and works.

Only time I have 'phone trouble' is when my main Internet service goes down. When the Internet comes back, the Obi recovers without me touching it.

Ditto for voip.ms here, too. A very simple, easy to use service, dirt cheap, decent quality, and tons of end-user controls (if you want to fiddle, otherwise ignore them).

Pretty much every calling feature under the moon is included gratis, including voice mail.

If I went with another VOIP provider, I'd lose my Triple Play Discount on my current Comcast service, making something that's already too expensive become even more so. And I'd be doing it just for the privilege of paying yet another company to have VOIP piggybacked onto the Comcast system which already does VOIP for me (admittedly with a narrower range of modem choices).

If I were dropping VOIP altogether, that might be a reason to cancel VOIP service and take the discount hit, but as long as I'm still limited to a burglar alarm that only works when the (notoriously unreliable) internet works, then what's the point.

When I got my alarm a while ago (maybe 5 or 6 years now?), they gave me a cellular one even though I still have a land line.

The point: is $1 + no-triple-play significantly cheaper than triple-play?

(the $1/month is only if you need a phone number; for outbound (alarm) calls only, a phone number isn't necessary).

Well, shit, I thought I had my problems solved, but I just can't catch a break.

I'd managed to order a VOIP cable modem from a company online which specializes in selling cable modems. They sent me the wrong modem, I'd ordered an SBC and they sent me a Cisco instead. No problem, I thought, since the Cisco was an even better modem than the SBC was going to be.

Turns out, the one they sent me was stolen. When I tried to activate it on Comcast, they told me that it was a rental-only model, not available for sale as a retail item, and that its serial number and mac address was actually still in their inventory as being one of their rental units. Comcast, understandably, won't activate it for me. Comcast were also quite understanding when I said that I would like to hang on to it to try to send it back and get my money back from the people who sold it to me.

I'm awaiting an email back from the sellers to see if they'll be honorable about it.

Now I have to shop for a goddamn modem AGAIN.

The problem is that there are not many out there which have the VOIP ports if you're specifically avoiding Arris units.

Current ending to this story is:

- I have the system fully working again. For now. Crossing my fingers it stays that way.

- I spent some time talking to a nice lady at the local Cisco office and going over my options. She was convinced that there's no reason for anyone at Comcast to be deliberately bricking my modems. But in terms of which modems I can get, there's pretty much no options other than the ones I've already been trying.

- As a last-ditch hail-mary pass, I ordered (and finally actually got) a used SBC D3GNV modem from a different internet seller. This is the model I'd originally wanted to get from the other internet seller, the one where the other seller sent me the wrong one, the Cisco that turned out to be a stolen Comcast rental modem still in Comcast's inventory.

- Like the Cisco before it, this used SMC D3GNV one is an XFinity-branded rental modem that they don't normally sell retail.

- However, I got lucky: this one wasn't a stolen modem still in Comcast's inventory. Supposedly this one was legally sold out of Comcast's inventory and was removed from Comcast's database the correct way. Thus it was OK for Comcast to activate it, and I had no problems like I'd had with the Cisco.

- It activated fine and it's working fine (so far). So everything is back to normal for now.

- Its firmware, when looking at it through the web browser, looks nearly identical to the last Arris modem that I'd tried which had died after a few months. This worries me. However this firmware is working better than the last one: At least this one saves its settings when it's rebooted. Crossing my fingers that this means the firmware is actually different under the hood, and that this one won't die after a few months.

- The thing is, this is literally the last modem I can try. I've run myself out of options. I had tried every other kind of VOIP-capable modem that was on the Comcast compatibility list. All the Arris units die after a few months, the Cisco unit isn't allowed to be activated as a customer-owned retail modem, and every other possible modem (a couple of Technicolor brand units are all that's left) are in the same boat as the Cisco unit (according to the gal at the comcast office). The gal at the Comcast office seemed to indicate that the Cisco unit might one day get sold at retail, but not yet.

So this SMC modem better last forever!

If this one doesn't last me forever, then I have to go another route for the burglar alarm. One weird option I have available to me is to double down on Comcast: They offer a package where, if I were to buy my burglar alarm through them, then it would use the internet to call the cops and have a cellular backup if the internet is down. I could get rid of the landline entirely, and just use their alarm system, and still get their "triple play discount" (where one of the three things is now the alarm instead of the landline). The math works out so that I would end up paying slightly less overall (like only a couple bucks less total) for a TV+Internet+Burglar package via Comcast than I am currently paying for TV+Internet+Landline via Comcast plus Burglar via ADT.

Though it's tempting to make that switch from a cost perspective, I really have problems with Comcast's customer service, and a burglar alarm isn't a place I want to be cutting corners on customer service. Also, Comcast's system would not be able to make use of my existing keypads and sensors, and would have a weird thing where I have to use a smartphone app to manage the alarm. Ew. So Comcast's system is not looking attractive to me at the moment.

At the same time though, ADT keeps raising their fees a few bucks every year. That bugs me. So maybe I'll call their customer retention department and see if I can get them to quit it.

Oh, and a final note: I was on the customer service line with Comcast and even though I changed the password on the modem's firmware, Comcast still has a wide open back door into the modem that they can get into and fiddle with its settings. From the internet. The guy could see all my menus and settings in the modem's firmware. Ew. So my paranoia about someone bricking the modem isn't unfounded.

docsis means basically, yes, they get to do that

You know, I'd put my money on Comcast doing it thru incompetence, before deliberate action.

I'm pretty sure the incompetence here is the fact that the back-end people aren't aware there's an intermittent modem-bricking Arris firmware bug, even while the field techs know about the bug. The field tech who came to my house was like "yeah, this is known issue, see, look here, this is a telltale sign, I could even tell from the line on the street that this was your problem..." etc. Yet, when I talked to the lady in the Comcast office, she said, "We have never heard of a problem with these Arris modems, we ship this particular model to customers all the time and never have problems, they work for years and years with no trouble..." etc.

So it's a problem where the company is too large for its own britches and there's not enough inter-department communication. There is a field problem, but the techs don't have a channel to properly report the bug up the chain to get it fixed.