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.
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|
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.
There are no SNR readings on those channels because they are not even locked. Have you tried power-cycling the modem again / lately to see if it will lock on to all channels ? Still no joy, you need a tech visit !
Tech time ! Good luck !
Did you ever resolve your problem? Any more clues for the rest of us?
I think I have exactly the same problem as you. I went from a fully working 100 Mbps plan with an Arris sb6121 to a 600 Mbps plan with a new Arris sb8200. Before hand I got 100 Mps down and 6 Mpbs up, just as I should have. Afterward I got 33 Mbps down and 17 Mbps up. So disappointing! My downstream bonded channels and spectrum analyzer graph are very similar. I have 29 QAM 256 channels locked, and 3 unlocked (all the ones under 500 MHz). I also have the OFDM channel showing as locked. And my downlink light is of course blue. So it sure seems odd to still be getting only the download speeds that a single QAM256 channel should be able to provide.
Given the pandemic situation, I really don't want to have a tech out. Also, I've got a very strong suspicious that this issue has nothing to do with any of my hardware, and everything to do with the configuration/firmware that comcast is giving to my Arris sb8200. A tech visit for this sure sounds like a royal waste of everyone's time to me.
Your post here did help me with one thing... I was thinking of trying a slower plan, in hopes that this modem would connect using fewer channels. But your results seem to indicate that probably won't help.
Anyone know if there is any way we can get the Arris sb8200 on Xfinity to connect using fewer channels, or to use only channels above 500MHz, such that the "not locked" channel problem becomes irrelevant? I'm guessing you'll say this is entirely controlled by the configuration file that Comcast controls, in which case... how do we get Comcast to fix that without suffering a tech visit?
One more related question...
Does anyone know if the 500-780MHz band in this spectrum analyzer result is normal? Or could it be a clue that there is a bandpass filter device somewhere that simply needs to be removed in order to allow the channels below 500MHz to lock successfully?