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BiggA

join:2005-11-23
EARTH

[Speed] What did Comcast do to my modem?

About 6 months ago, I moved from an apartment to a house on the same Comcast system. I have a Motorola SB6141 modem. The day after I called to move the service (a couple days before I moved), the speeds went to crap (60mpbs to a couple mbps), but I didn't really care, as I was moving. I moved into the house with 3 roommates, and for a week, we had horrific problems getting the internet working properly. It would often be .5mbps, with the full 12mbps upload. After days of swapping it to basically every different cable in the house, checking levels over and over and over, and calling Comcast several times and re-provisioning the modem over and over, they sent a guy out, he checked everything, and told me to try a new modem from the Comcast office. I got the new modem, and voila! everything worked fine.

Fast forward 6 months, and I'm tired of paying their absurd rental fees for a modem, so I tried swapping in the owned modem, but it was only giving me about 10mbps. I called them, and after getting bounced around their tech support several times, got it re-provisioned and working correctly (PB around 100mbps, evening out to about 60mbps). This morning, it was still working fine, so I returned the rented modem to them, and I come home and it's broken again. After two reboots, it now gets 37mbps, which is even weirder.

What the heck did they do to my modem and how do I get them fix it? Re-provisioning doesn't change anything, and it still intermittently breaks. They can't even figure out what's wrong, and they're usually unwilling to help. I don't want to have to buy a new modem because these idiots broke mine. When the other cable company gets more channel or Comcast enables their data cap, I also can't really switch to the other cable company with a modem that Comcast broke and expect them to do anything about Comcast's problem, so unless I can get Comcast to fix it, I'll have to buy a new one.


travelguy

join:1999-09-03
Santa Fe, NM

AFAIK, PowerBoost is long gone. The problem isn't necessarily your modem, it could just be that the node you are on now is saturated. Check the signal levels when you are seeing poor performance, just to make sure you don't have a bad connection. Beyond that, there's not much you can do besides calling Comcast.



Darknessfall
Premium
join:2012-08-17
kudos:5
Reviews:
·Comcast
·AT&T U-Verse

1 edit

said by travelguy:

AFAIK, PowerBoost is long gone. The problem isn't necessarily your modem, it could just be that the node you are on now is saturated. Check the signal levels when you are seeing poor performance, just to make sure you don't have a bad connection. Beyond that, there's not much you can do besides calling Comcast.

PB isn't gone in all markets. When referring to residential, it's gone on the upstream for all markets, but some still have PB on the downstream. PB is more common on Blast in areas. Only one state has PB on Performance now as far as I know.

DiffProbe release. January 2012. Build 1008.
Shaper Detection Module.

Connected to server 38.107.216.34.

Estimating capacity:
Upstream: 5866 Kbps.
Downstream: greater than 200 Mbps.


PB_Not_Dead

@comcast.net

said by Darknessfall:

PB isn't gone in all markets. It's gone on the upstream for all markets, but some still have PB on the downstream. PB is more common on Blast in areas. Only one state has PB on Performance now as far as I know.

Proving once again that the only safe statement anyone can make regarding any Comcast service is YMMV.

Business Class Starter (16/3):


DiffProbe release. January 2012. Build 1008.
Shaper Detection Module.

Connected to server 80.239.142.202.

Estimating capacity:
Upstream: 7755 Kbps.
Downstream: 21017 Kbps.

The measurement will take upto 2.5 minutes. Please wait.

Checking for traffic shapers:

Upstream: Burst size: 4822-4985 KB;
Shaping rate: 3210 Kbps.

Downstream: Burst size: 9838-10041 KB;
Shaping rate: 17024 Kbps.



Darknessfall
Premium
join:2012-08-17
kudos:5
Reviews:
·Comcast
·AT&T U-Verse

said by PB_Not_Dead :

said by Darknessfall:

PB isn't gone in all markets. It's gone on the upstream for all markets, but some still have PB on the downstream. PB is more common on Blast in areas. Only one state has PB on Performance now as far as I know.

Proving once again that the only safe statement anyone can make regarding any Comcast service is YMMV.

Business Class Starter (16/3):


DiffProbe release. January 2012. Build 1008.
Shaper Detection Module.

Connected to server 80.239.142.202.

Estimating capacity:
Upstream: 7755 Kbps.
Downstream: 21017 Kbps.

The measurement will take upto 2.5 minutes. Please wait.

Checking for traffic shapers:

Upstream: Burst size: 4822-4985 KB;
Shaping rate: 3210 Kbps.

Downstream: Burst size: 9838-10041 KB;
Shaping rate: 17024 Kbps.


You're on BC though. I was referring to(but forgot to mention it since I forgot all about BC) residential plans. Fixed

OP, can you post your signals?

BiggA

join:2005-11-23
EARTH
reply to travelguy

Not possible. The rental modem was consistently 59+mbps for 6 months. When on wireless and when everything is working, the speeds peak over 70mbps, on wired, they go over 100mbps, before settling around 60mbps. I'm on Blast!


BiggA

join:2005-11-23
EARTH
reply to Darknessfall

Click for full size
Sure. Everything except the power brick and the modem itself is the same as with the rented modem, so we know it's something to do with the configuration of the modem and/or Comcast's system in relation to that particular modem.

BiggA

join:2005-11-23
EARTH
reply to Darknessfall

It's a 650mhz system, that is showing 8 channels, although they claim there are only 6, with 4 configured for HSI, and the other two for STBs/CDV/other crap.



gar187er
I do this for a living

join:2006-06-24
Dover, DE
kudos:4

said by BiggA:

It's a 650mhz system, that is showing 8 channels, although they claim there are only 6, with 4 configured for HSI, and the other two for STBs/CDV/other crap.

docsis channels, are docsis channels. the only stbs that use docsis are X1, and EMTAs and HSI modems all share the same channels.

a 650 system?!?! really? i thought i had it bad working in a 750 system....
--
I'm better than you!

DanM64

join:2013-01-10
Mokena, IL
reply to BiggA

Your upstream power levels are too high. You're pushing the max allowed for upstream channel bonding. That is likely the source of your issues.


BiggA

join:2005-11-23
EARTH

My issue is downstream, not upstream, and the other modem worked just fine in the exact same location.


andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL

1 recommendation

Upstream problems can affect downstream if the ACK packets acknowledging a packet received get lost or held up.



IowaCowboy
Iowa native
Premium
join:2010-10-16
Springfield, MA
kudos:1
reply to BiggA

Truck roll time.

Probably a bad drop or a plant issue.


BiggA

join:2005-11-23
EARTH

I've already stated TWICE that the rental modem was 100% fine for 6 months. The only variable that changed is the modem and it's power adapter. Everything else is identical. Due to when it happened, right after I put a move request in, it seems that Comcast did something to my modem. Also, at the beginning of that, they came out, and tested the levels, and everything was excellent.


BiggA

join:2005-11-23
EARTH
reply to IowaCowboy

Also, with a few exceptions, it's an all-or-nothing thing. It's either doing ~60mbps or ~.5mbps.



IowaCowboy
Iowa native
Premium
join:2010-10-16
Springfield, MA
kudos:1
Reviews:
·Verizon Broadban..
·Comcast

Then it sounds like they're not pushing the correct config file to your modem. Maybe you need to call and ask to speak to tier 2 tech support or even advanced tech support. It sounds like you are getting the runaround from the tier one tech support.

Maybe the new house that you moved into has some electrical issues. When was it built. Maybe you could post in the DSLR home improvement forum. Electrical issues can cause Cable TV/computer equipment to act up. My old house in Iowa built in 1949 had electrical issues that caused the TV to feed current into the cable line and almost fried a cable box. I had to go back to analog expanded basic. My current house is built in 1988 and has modern wiring and I have zero grounding issues whatsoever.
--
I've experienced ImOn (when they were McLeod USA), Mediacom, Comcast, and Time Warner and I currently have DirecTV. They are much better than broadcast TV.

I have not and will not cut the cord.


BiggA

join:2005-11-23
EARTH

They've re-provisioned it about a dozen times, and it sometimes gets 60mbps... how would it work correctly sometimes without the correct config file?

This house was built in 1999, and it's possible it has issues, but that wouldn't explain why the other modem was rock solid for 6 months of heavy use (300-600GB/mo), in two different locations in the house (I had to move the router/modem for wireless signal reasons).

I'm pretty baffled, as I don't know what they can do to a modem other than mess up the provisioning, which they've already re-done a whole bunch of times. What's even weirder is that I'm now getting some middle-ground results in the 25-40mbps range, which I've only seen a couple of times before.



Caddyroger
Premium
join:2001-06-11
To the west
reply to BiggA

Did you ever think it is a bad modem. New stuff some times break down in a couple of months.
--
Caddy


mrschultz02

join:2007-09-10
Media, PA
reply to BiggA

said by BiggA:

I've already stated TWICE that the rental modem was 100% fine for 6 months. The only variable that changed is the modem and it's power adapter. Everything else is identical. Due to when it happened, right after I put a move request in, it seems that Comcast did something to my modem. Also, at the beginning of that, they came out, and tested the levels, and everything was excellent.

As someone else said, the modem could be going bad.

Also when you swapped modems you had to mess with the cables, have you reseated all connections? Something as simple as disconnecting and reconnecting every connection you can find between the modem and the drop can help with bad signal levels. Also how many splitters between the drop and the modem, if you have more than one redo the wiring so there is only one.

Also like others have said, your upstream power is way too high, got to get that down under 50 if you want a stable connection since it wanders a bit during the day. Are you seeing a lot of reboots of the modem? Check the log. If I saw 51db upstream on my modem I know it's going to hit 52 soon and reboot.

jobias

join:2006-01-18
Knoxville, TN
reply to BiggA

Intermittent issues with a single device tend to point towards that device as the source of the problem.
If you still had the rental, I'd recommend hooking it up to get the signal levels it's reporting as well. If it's reporting acceptable upstream power levels, it'd be a strong indication that your modem's gone bad.
Since you don't, I'd either head to an electronic shop and pick up a new modem, or grab another rental from comcast, and use that to check the signal level.
If the signal level is bad with a new one, call in and get a tech out.


BiggA

join:2005-11-23
EARTH
reply to Caddyroger

Yes, it's possible. I just have a hard time believing that when it went south the day after I called in to move my service, and works sometimes. I'd think it would either work or it wouldn't not halfway in-between and intermittently. That, and of the many, many pieces of electronics I've seen go south, I've never seen a cable modem go south.


BiggA

join:2005-11-23
EARTH
reply to mrschultz02

As I said before, I had tested with this modem many, many times, and all I did when swapping them recently was unplug one and plug the other one in.


BiggA

join:2005-11-23
EARTH
reply to jobias

I had those somewhere. Let me see if I can find them.


BiggA

join:2005-11-23
EARTH

And apparently I don't have them. I suppose it could be possible that there is something wrong with the plant and the Ubee was just a bit better at dealing with a bad upload? It just seems odd that the upload would go south but the upload speed would be rock solid. I get how the upload can affect the download speed, but I would think the upload speed would have to go south first...


obckilroy

join:2011-11-16
reply to BiggA

Just for kicks did you check the power supply? I've seen some 9v supplies powering modems...


BiggA

join:2005-11-23
EARTH

It's whatever came with the modem.


obckilroy

join:2011-11-16

gotcha, thought maybe during the move it got switched with another pack


Drizew

join:2004-09-17
Los Lunas, NM
reply to BiggA

You've already been told how to help yourself. If you don't want to take the advice, thank the users and move on.

Your particular modem could be sensitive to the signals it gets. Have them fix the high UL power issue, and then post your results.


BiggA

join:2005-11-23
EARTH

I don't know what to do. I'm stuck between a rock and a hard place on this one. Comcast screwed it up, and they have no clue what's wrong with it, and won't fix it, or even admit there's a problem. That wouldn't explain why it was getting slow speeds right before I moved out of the other place...


BiggA

join:2005-11-23
EARTH

At this point, they owe me about $100 and a new modem, but I know I'm not getting anything from those idiots.