Xfinity plant
Community Forum
Xfinity globe

Slow down <1mbs, Fast UP, many splits/bad wirings ? (PICS)

New Poster

Slow down <1mbs, Fast UP, many splits/bad wirings ? (PICS)

I currently pay and have been paying for the 100mbs option of Xfinity internet.  I noticed a problem when I couldn't even stream youtube videos at 360p.  Pictures load like when I was on a 14k modem. Looking at various download speed tests I am getting sub 1mbs , rarely peaking to ~20mbs then immediately back down to sub 1mbs. 



more recent

a few hours ago




This problem has persisted throughout the years I have lived here with Comcast as my provider.  It has only gotten worse with time.  I pay too much to recieve so little.  I have done the song and dance of reset modem etc, and had someone come to take a look at it some many months ago from comcast, he saw a problem and had someone else come out assist him. It was better for a short time and is now in terrible shape and shows no signs of improving. This problem has persisted through different computers/os/modems/ coax cables etc. If there was something to change on my end, I have.


Researching the problems and looking at the symptoms and modem error codes:


Arris SBG6700-AC is my modem


SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out

Started Unicast Maintenance Ranging - No Response received - T3 time-out

No Ranging Response received - T3 time-out


Levels from today:


Channel Lock Status Modulation Channel ID Frequency Power SNR Corrected Uncorrectables
1 Locked QAM256 21 729000000 Hz -11.4 dBmV 37.8 dB 2 0
2 Locked QAM256 17 705000000 Hz -12.1 dBmV 37.2 dB 682576 2165430
3 Locked QAM256 18 711000000 Hz -12.1 dBmV 37.2 dB 241786 943630
4 Locked QAM256 19 717000000 Hz -11.2 dBmV 37.5 dB 931 0
5 Locked QAM256 20 723000000 Hz -11.4 dBmV 37.5 dB 6 0
6 Locked QAM256 22 735000000 Hz -10.1 dBmV 38.0 dB 0 0
7 Locked QAM256 23 741000000 Hz -10.9 dBmV 37.6 dB 0 0
8 Locked QAM256 24 747000000 Hz -10.8 dBmV 27.5 dB 2473583 1917796


Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 6 5120 Ksym/sec 29400000 Hz 44.0 dBmV
2 Locked ATDMA 5 5120 Ksym/sec 35800000 Hz 42.5 dBmV
3 Locked ATDMA 7 5120 Ksym/sec 23000000 Hz 42.5 dBmV

another pic of the levels  (older)
bad signal.png




Everything I see with similar issues points to too many splits.


I decided to go look for myself, maybe I can see a problem. Its a light rain outside.  Since I never go on this side of the building I was suprised see the cover thrown to the ground and the wires left dangling in the rain.



Upon investigation here's what I found. If you look at the picture 2 cables come from the pipe down there to supply the building.  Then one of said lines goes into a 4way split. From here some apartments have 2cables running into them.  Not mine though.




With my apartment (and I am assuming the lables are correct).  From what I finger traced. 1 of the two supply cables goes into a 4way split. then from the 1 of the 4 it then goes into an 8way split from there it may be split again. I see a two way split thrown in there.. You can almost see it from the picture. 8 Apartments, with 2 source cables feeding the building. Some apartments are getting half a source cable(like #23 you see there). I am just getting 'badword'ed?  imgur album link


I would like some help/answers/recompense.


Edit: I should add that it is worse at night through early morning when I am typically on the computer.  I work nights, come home and game/stream etc.  Usually sleep during the day.  However, days I'm off-work it seems healthier during the day.


Re: Slow down <1mbs, Fast UP, many splits/bad wirings ? (PICS)

Perhaps it would be best to book a tech to come and sort this one out.


Re: Slow down <1mbs, Fast UP, many splits/bad wirings ? (PICS)

What @EG said. Your performance is lousy because your signals are lousy. Looks like you are going to need a tech to sort it out. FYI it's fine if those cables get wet, they are designed to be exposed to the elements. 


I've asked a Comcast employee to help you. You should expect a reply in this thread. 

"Keepin' it clean since '09"
I am not a Comcast employee, just a moderator.
Official Employee

Re: Slow down <1mbs, Fast UP, many splits/bad wirings ? (PICS)

Hi Scipio5, 


I can help get a tech out to have this taken care of for you. Please send me a private message by clicking on my name, "ComcastChe" then click private message me. In the body of this message please verify your first and last name, street address including city state and zip code, and the account number or phone number associated with your services. 

New Poster

Re: Slow down <1mbs, Fast UP, many splits/bad wirings ? (PICS)

@nerdburg @ComcastChe


thank you 

Official Employee

Re: Slow down <1mbs, Fast UP, many splits/bad wirings ? (PICS)

You're very welcome! 

New Poster

Re: Slow down <1mbs, Fast UP, many splits/bad wirings ? (PICS)

I would like to give a little update to my situation.  I take a day off work, excited to finally get this fixed.  It's been raining today, so I go outside at 1pm and put some carboard down by where the splitters are so that the tech doesn't have to get his boots muddy. 3pm rolls by and I start to get worried.  A gentleman calls me from the dispatch saying the driver is running late.  No problem, I've got all day.


4:47 I recieve a call from the comcast number and the robot lady tells me the tech is outside and I should greet them.  

I excitedly open the door, nobody there.  Go to parking lot, nobody there.  I decide to wait, maybe he signed in early. Nobody ever shows up... then I get a call saying sorry we missed you. I immediately call comcast main number and talk to a very nice lady who after talking to the dispatch for ~ 26minutes, informs me that I have to reschedule to Saturday. 


Not gonna lie, kinda ticked about it.  Either the tech went to the wrong place or literally lied about being here.