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Extremely inconsistent speeds, directly from the cable modem

Frequent Visitor

Extremely inconsistent speeds, directly from the cable modem

Just started having speed issues yesterday. I currently pay for 105Mbps Down/10Mbps Up Blast speeds. Speeds have been fine for the last six months up until now.

 

Basically... I initially thought it was my router, but both last night and this morning I tried running speed tests while connected directly to my cable modem (Arris Surfboard sb6121), and regardless of how many times I power cycle the modem, the same thing happens:

 

Speed test #1 - 25Mbps down/10Mbps up

 

Speed test #2 - 1.5Mbps down/10Mbps up

 

Speed test #3 - .5MBps down/10Mbps up

 

Speed test #4 - .25Mbps down/10Mbps up

 

Speed test #4 - 85Mbps down/10Mbps up

 

Speed test #5 - .5Mbps down/10Mbps up

 

...and so on. It's ALL OVER the radar, but 7/10 times, it'll be horribly crawling speeds.

 

Yes, I've read that SB6121 modems are considered EOL now, however from what I understand, that's just the models that comcast themselves installed/rented. I bought this retail model on my own, and I am of the understanding that it should continue to work fine. Docsis 3 is Docsis 3, after all.

 

This is terribly frustrating. I know if I call Comcast and get them to send a tech out, they'll charge me ~$75 for the visit. I'd like to avoid that.

 

Here is the page on their official support forums detailing that the SB6121, while being listed as EOL, is perfectly fine to continue using if you bought your own retail version

http://forums.xfinity.com/t5/Home-Networking-Router-WiFi/SB6121-6141-End-of-Life-Details/td-p/270800...

Expert

Re: Extremely inconsistent speeds, directly from the cable modem

Endymion86 wrote:

Docsis 3 is Docsis 3, after all.

It's not quite that simple. Newer DOCSIS 3 modems have more multiple bonded channels (up to 32), resulting in a fatter pipe to the internet / more available bandwidth which you share with your neighbors. That modem only has 4 and won't help if you are on a congested cable segment.

Where are you testing your speeds ? Is there a router involved ? If so, is this via a WiFi connection ?


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Frequent Visitor

Re: Extremely inconsistent speeds, directly from the cable modem

I have been testing my speeds on speedtest.net.

 

This was on a wired connection directly from the Cable Modem to my laptop.

 

 

Expert

Re: Extremely inconsistent speeds, directly from the cable modem

Test here too;

 

http://speedtest.xfinity.com/

 

What do the modem's signal stats look like ? Try getting them here; http://192.168.100.1

Please post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.





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Contributor

Re: Extremely inconsistent speeds, directly from the cable modem

 

Try accessing your router page ( it might be 192.168.100.1)  and seeing if the uncorrectable error rate are "off the charts" like in the hundreds of thousands or in the negative .

If so, maybe might be some hardware problem if that is the case, I think.

 

Also, Have you installed any line splitters in your coaxial cable coming in from the street?

 

Hope you get this resolved.

 

 

 

 

Expert

Re: Extremely inconsistent speeds, directly from the cable modem

"Routers" can't be accessed at that address. Only straight cable modems and combo gateway devices in bridge mode can..

The signal stats will reveal a connectivity problem if one exists..


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Problem Solver

Re: Extremely inconsistent speeds, directly from the cable modem


Endymion86 wrote:
 - snip -

 I know if I call Comcast and get them to send a tech out, they'll charge me ~$75 for the visit. I'd like to avoid that.

 - snip -

Comcast says this can be avoided if you sign up for Comcast's service protection plan.

Get it for a couple months, you only have to keep the plan 60 days after a covered service visit.

 

http://www.xfinity.com/spp

http://www.xfinity.com/spp/terms.html

 

Frequent Visitor

Re: Extremely inconsistent speeds, directly from the cable modem

Managed to get in contact with a couple different reps at Comcast who were browsing the /r/Comcast and /r/Comcast_Xfinity subreddits I posted on earlier today on Reddit. Both of them checked my signal strength numbers after I gave them my modem's MAC address, and both came back saying my SNR numbers were much lower than they should be, and that it was a pole-premise issue. My guess would be that the evil squirrels who originally chewed through the cable line and caused issues when I first moved into this place are back at it again. They're sending a tech out tomorrow to check things out. I sincerely hope that fixes the issue!

Thanks again for the advice though, guys. 

Frequent Visitor

Re: Extremely inconsistent speeds, directly from the cable modem

Comcast says this can be avoided if you sign up for Comcast's service protection plan.

Get it for a couple months, you only have to keep the plan 60 days after a covered service visit. 



 

So, since the appointment hasn't been confirmed via the automated phone call yet (although it is scheduled in their system), can I apply for the Service Protection Plan now, keep it for two months, then cancel it, and only have to pay the $16 or so?

 

Problem Solver

Re: Extremely inconsistent speeds, directly from the cable modem

Endymion86 wrote:


So, since the appointment hasn't been confirmed via the automated phone call yet (although it is scheduled in their system), can I apply for the Service Protection Plan now, keep it for two months, then cancel it, and only have to pay the $16 or so?


 

yep, thats my understanding.   i don't see other Comcast replies at moment, but there is this,

http://forums.xfinity.com/t5/Customer-Service/Internet-shut-off-with-no-permission/m-p/2627122#M8811...

 

Expert

Re: Extremely inconsistent speeds, directly from the cable modem


Endymion86 wrote:

Comcast says this can be avoided if you sign up for Comcast's service protection plan.

Get it for a couple months, you only have to keep the plan 60 days after a covered service visit. 



 

So, since the appointment hasn't been confirmed via the automated phone call yet (although it is scheduled in their system), can I apply for the Service Protection Plan now, keep it for two months, then cancel it, and only have to pay the $16 or so?

 


I have the plan but in your scenario would not be a charge anyway. they 'own' (maintain) to your demarcation point (the cable box on the outside of your home).



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Frequent Visitor

Re: Extremely inconsistent speeds, directly from the cable modem

Hey guys, just wanted to update. Tech came out today, shimmied up the pole, and sure enough, the squirrels had chewed the heck out of it. All fixed now. Smiley Happy Thanks again for all the suggestions.