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Modem upgrade decreased download speed

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Frequent Visitor

Modem upgrade decreased download speed

We have 100Mbps down/ 5Mbps up plan. I recently upgraded our cable modem from a Ubee DDM3513 (now unsupported) to an Aris SB8200 and our download speed has decreased from 110Mbps to 30Mbps. I have tried reactivating the new modem multiple times but the issue persists.

 

I suspect that the modem is being misconfigured during the provisioning process. How can I get someone to look into this?

 

I've attached the modem status page along with a spectrum analyzer plot.

 

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Frequent Visitor

Download speed significantly reduced

I first posted about this a couple of weeks ago but have recieved no response and the phone support is useless. So here I go again ...

 

I recently upgraded my cable modem from a old Ubee DOCSIS 3.0 unit to an Arris SB8200 and my download speed has decreased from 100-110Mbps to less than 30Mbps. I would like to ensure that nothing went wrong during the provisioning stage (e.g. wrong configuration) that might have caused this.

 

I have tried factory resetting the modem and provisioning multiple times but nothing has worked. Modem download channel status info is below, SNR looks good but there a 5 unlocked channels.

 

Downstream Bonded Channels
Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
29 Locked QAM256 663000000 Hz 5.3 dBmV 41.3 dB 0 0
1 Not Locked Unknown 483000000 Hz -44.9 dBmV 0.0 dB 0 0
2 Not Locked Unknown 489000000 Hz -42.3 dBmV 0.0 dB 0 0
3 Not Locked Unknown 495000000 Hz -40.6 dBmV 0.0 dB 0 0
4 Not Locked Unknown 507000000 Hz -37.2 dBmV 0.0 dB 0 0
5 Not Locked Unknown 513000000 Hz -25.9 dBmV 0.0 dB 0 0
6 Locked QAM256 519000000 Hz -17.4 dBmV 29.3 dB 7724 0
7 Locked QAM256 525000000 Hz -10.2 dBmV 31.3 dB 11 0
8 Locked QAM256 531000000 Hz -4.5 dBmV 38.7 dB 0 0
9 Locked QAM256 543000000 Hz 1.5 dBmV 40.7 dB 0 0
10 Locked QAM256 549000000 Hz 2.6 dBmV 41.4 dB 0 0
11 Locked QAM256 555000000 Hz 3.4 dBmV 41.5 dB 0 0
12 Locked QAM256 561000000 Hz 3.8 dBmV 41.6 dB 0 0
13 Locked QAM256 567000000 Hz 3.9 dBmV 41.1 dB 0 0
14 Locked QAM256 573000000 Hz 4.0 dBmV 41.0 dB 0 0
15 Locked QAM256 579000000 Hz 4.1 dBmV 41.5 dB 0 0
16 Locked QAM256 585000000 Hz 4.4 dBmV 41.6 dB 0 0
17 Locked QAM256 591000000 Hz 4.1 dBmV 41.6 dB 0 0
18 Locked QAM256 597000000 Hz 4.2 dBmV 41.6 dB 0 0
19 Locked QAM256 603000000 Hz 4.0 dBmV 40.5 dB 0 0
20 Locked QAM256 609000000 Hz 3.9 dBmV 41.3 dB 0 0
21 Locked QAM256 615000000 Hz 4.2 dBmV 41.4 dB 0 0
22 Locked QAM256 621000000 Hz 4.0 dBmV 41.3 dB 0 0
23 Locked QAM256 627000000 Hz 4.6 dBmV 41.3 dB 0 0
24 Locked QAM256 633000000 Hz 4.8 dBmV 41.4 dB 0 0
25 Locked QAM256 639000000 Hz 5.1 dBmV 41.4 dB 0 0
26 Locked QAM256 645000000 Hz 5.2 dBmV 41.4 dB 0 0
27 Locked QAM256 651000000 Hz 5.4 dBmV 41.6 dB 0 0
28 Locked QAM256 657000000 Hz 5.5 dBmV 41.4 dB 0 0
30 Locked QAM256 669000000 Hz 5.4 dBmV 41.4 dB 0 0
31 Locked QAM256 675000000 Hz 5.3 dBmV 41.0 dB 0 0
32 Locked QAM256 681000000 Hz 5.1 dBmV 41.3 dB 0 0
159 Locked Other 722000000 Hz 7.7 dBmV 40.5 dB 107367389 0

 

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Diamond Problem Solver

Re: Download speed significantly reduced

I’m not sure where you think SNR looks good, take a look at channels 1-7 that have no SNR at all and negative to non-existent downstream signal. If you were using a dated modem before, what are the chances that your cabling (cable, splitters etc) are dated too?

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Frequent Visitor

Re: Download speed significantly reduced

With regards to the SNR, I was referring to the locked channels. In any event, I have connected the modem directly to the cable from the street and I see similar signal levels.

 

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Expert

Re: Download speed significantly reduced

There are no SNR readings on those channels because they are not even locked. Have you tried power-cycling the modem again / larely to see if it will lock on to all channels ? Still no joy, you need a tech visit !



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Frequent Visitor

Re: Download speed significantly reduced

Yep, I have power cycled the modem many times and those five channels have never locked.

 

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Expert

Re: Download speed significantly reduced

Tech time ! Good luck !



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
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Frequent Visitor

Re: Download speed significantly reduced

Thanks.

 

Unfortunately, I need to wait until I have a few free hours to spend on the phone 😉