K

Visitor

 • 

4 Messages

Wednesday, July 2nd, 2025 3:22 PM

Slower Upload Speed after Gigabit Upgrade

I was on a 400/40 plan (And often got 475/43 in real use), and then after upgrading to the gigabit plan, my modem reprovisioned, and now my speedtest is 700/5. I understand I will not get the full gigabit down speed because my modem is a Motorola MB8600 (which comcast says can only reach speeds of about ~930 down), but I should be getting at least the 40 up that I had on my previous provisioning. None of the equipment changed, and I have restarted my modem multiple times, and done a factory reset twice letting it reprovision twice with no change the the ~5mbit upload speeds.

I have already used the comcast automated assistant, and it just wants me to upgrade my modem because my modem does not support the speed of my current plan.

I understand that my modem does not support the full download speed, but I was already getting the 40mbit upload speed before the plan upgrade. I just want that 40mbit back.

Any suggestions? Comcast support, if you are listening, can you check that you are sending my modem the right provisioning file?

I am posting my connection stats below to show it's not a signal problem either:

Connection

Top of Form

   Startup Sequence

 

 

   Startup Step

Status

Comment



  

   Acquire Downstream Channel

501000000 Hz

Locked


  

   Upstream Connection

OK

Operational


  

   Boot State

OK

Operational



  

   Configuration File

OK


  

   Security

Enabled

BPI+


  

 

   Connection Status

 

 

   System Up Time

0 days 07h:24m:18s

 


  

   Network Access

Allowed

 


  

 

   Downstream Bonded Channels

 


  

   Channel

Lock Status

Modulation

Channel ID

Freq. (MHz)

Pwr (dBmV)

SNR (dB)

Corrected

Uncorrected

   1

Locked

QAM256

20

501.0

3.3

43.6

0

0

   2

Locked

QAM256

1

387.0

2.4

42.6

1

0

   3

Locked

QAM256

2

393.0

2.6

42.8

1

0

   4

Locked

QAM256

3

399.0

2.9

43.1

1

0

   5

Locked

QAM256

4

405.0

2.6

43.0

1

0

   6

Locked

QAM256

5

411.0

2.7

42.6

1

0

   7

Locked

QAM256

6

417.0

2.8

43.0

5

0

   8

Locked

QAM256

7

423.0

2.8

43.1

0

0

   9

Locked

QAM256

8

429.0

2.7

43.0

0

0

   10

Locked

QAM256

9

435.0

2.6

43.1

1

0

   11

Locked

QAM256

10

441.0

2.4

42.9

0

0

   12

Locked

QAM256

11

447.0

2.6

43.1

0

0

   13

Locked

QAM256

12

453.0

2.8

43.2

0

0

   14

Locked

QAM256

13

459.0

2.7

43.2

0

0

   15

Locked

QAM256

14

465.0

2.7

43.1

0

0

   16

Locked

QAM256

15

471.0

2.9

43.3

0

0

   17

Locked

QAM256

16

477.0

3.2

43.4

0

0

   18

Locked

QAM256

17

483.0

3.2

43.5

0

0

   19

Locked

QAM256

18

489.0

3.3

43.7

0

0

   20

Locked

QAM256

19

495.0

3.3

43.6

0

0

   21

Locked

QAM256

21

507.0

3.5

43.8

0

0

   22

Locked

QAM256

22

513.0

3.4

43.9

0

0

   23

Locked

QAM256

23

519.0

3.3

43.7

0

0

   24

Locked

QAM256

24

525.0

3.4

43.8

0

0

   25

Locked

QAM256

25

531.0

3.4

43.8

0

0

   26

Locked

QAM256

26

537.0

3.4

44.0

0

0

   27

Locked

QAM256

27

543.0

3.6

44.1

0

0

   28

Locked

QAM256

28

549.0

3.6

43.9

0

0

   29

Locked

QAM256

29

555.0

3.7

44.1

0

0

   30

Locked

QAM256

30

561.0

3.9

44.1

0

0

   31

Locked

QAM256

31

567.0

4.4

44.3

0

0

   32

Locked

QAM256

32

573.0

4.2

44.3

0

0

   33

Locked

OFDM PLC

193

690.0

6.3

44.6

16099021

0

   34

Locked

OFDM PLC

194

957.0

5.4

44.5

4188258

0

 

   Upstream Bonded Channels

 


  

   Channel

Lock Status

Channel Type

Channel ID

Symb. Rate (Ksym/sec)

Freq. (MHz)

Pwr (dBmV)

   1

Locked

SC-QAM

1

5120

16.4

42.8

   2

Locked

SC-QAM

2

5120

22.8

42.3

   3

Locked

SC-QAM

3

5120

29.2

42.0

   4

Locked

SC-QAM

4

5120

35.6

42.3

 

 

Accepted Solution

Visitor

 • 

4 Messages

13 hours ago

I wanted to provide an update for anyone in a similar situation. The Hitron CODA56 immediately solved the issue. So it would seem the MB8600 isn't compatible (or isn't allowed to be configured properly) for the xfinity gigabit service config profile. The following is a summary of my experience in case anyone else has the same issue:
1) Had a Motorola MB8600 working great at 400/40 with real world speeds of 475/47.

2) Decided to upgrade to gigabit because there was a good offer available, and accepted the offer.

3) The MB8600 did not automatically reprovision, so I restarted the modem an hour later. And it updated the provisioning profile at that point.

4) The real world speed tests were 740/5. Only 5mbps upload was unacceptable to me.

5) Googled for hours trying to see if there was a way to make the MB8600 work, and tried multiple restarts and full factory resets, allowing it to download a new provisioning file. No improvements or changes.

6) Tried the automated assistant feature on the xfinity portal, but it would only tell me that my equipment was not able to reach the speeds of my plan.

7) Gave up and ordered a Hitron CODA56. Received it.

8) Used the mobile app to swap the equipment, providing it the new modem MAC address.

9) After about 15 minutes and a couple of restarts, it was up and running and I now get over 1100/120, very happy.

If this applies to your situation, I know it's not free, but just save time, buy a modem on the recommended equipment list.

Visitor

 • 

4 Messages

20 hours ago

If this is a mid split / "next gen speeds" support issue where the MB8600 can't (or isn't allowed) to work with the network upgrades, I can accept that. But how can I confirm my area supports next gen before buying a new modem?

Referencing this thread:
https://forums.xfinity.com/conversations/your-home-network/my-plan-has-much-lower-upload-speed-that-it-should/68615698d2b4741a720cc422?commentId=68617303d2b4741a720f8f43

(edited)

Visitor

 • 

4 Messages

20 hours ago

I went ahead and ordered a Hitron CODA56 which should arrive later today to see if this is an MB8600 compatibility issue. I need at least 20mbit upload speeds but I will never use equipment rented from comcast.

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