Topic '[Connectivity] SB8200 Signals. Is this normal or bad?' in forum 'Comcast XFINITY' - dslreports.com

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Sat, 22 Jul 2017 14:21:56 EDT

halfband posted : You seem to have a lot going on. The modem should have zero impact on how the thermostats get IP addresses (or were they trying to get out to an IP in which case the router SW update may have cleared some port access exceptions.) You might be better off starting another thread, post your signal levels etc. Also just make sure everything got booted up in the right order; modem, router, then all connecting devices.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Sat, 22 Jul 2017 11:15:29 EDT

njweb posted :

said by njweb:

said by mikev:

Comcast's current configuration for the SB8200 makes it very sensitive to RF signals in the MoCA frequencies (~1.2-1.3 GHz in this case). This has the consequence of creating both corrected and uncorrectable errors if there are strong MoCA signals present (like from X1 cable boxes), even though the DOCSIS signal levels are normal and well within specifications.

Unfortunately, this is the result of a solution to an issue with provisioning the SB8200 on certain CMTSes in use on Comcast's network in some areas. The problem CMTSes will be upgraded later this year, and at that point Comcast will be able to return the SB8200's configuration so that it won't be sensitive to those MoCA signals anymore.

In the meantime, a simple MoCA filter can significantly improve things, if you're looking for a quick fix without buying a new modem and returning the SB8200.

Thanks for the valuable post. I am having major internet connectivity issues with my SB8200 suddenly. 3 reboots needed today alone (every few hours performance degrades to the point where web sites do not load; right after rebooting they load lightning fast and speedtest shows 13 ms ping time and 211 Mbps down and 12 Mbps up which is more than my 200/10 plan).

Signals are within spec.
Downstream power ranges between 3.2 and 6.6 dBmV depending on the channel.
SNR is 40.1 to 42 dB on the 28 QAM256 channels; the 1 'Other' channel (not QAM256) has a SNR of 38.8.
Upstream power is between 44.5 and 46.8 dBmV depending on the channel.

Most likely this issue can be attributed to Comcast switching me over to D3.1 today (i.e. my SB8200 always had only green lights since I got it and I have had it before they came out to amazon - ordered it directly from Arris). However today I got the blue light on the downstream side.
Might have to rename it the blue light of death in my case...

I had 16 QAM256 downstream channels till today; as of this morning I now have 29 downstream channels (28 are QAM256 and 1 is of type 'Other'; the 'Other' has a small number of (just 91) corrected errors' since I factory / hard reset the modem today.

My SB8200 also runs hot.

Is the officially supported Motorola MB8600 a better bet? (it runs cooler for one thing and I assume it does not have the RF sensitivity issue of the SB8200 on some CMTSes).

My SB8200 seems to have been running more stable since last night (knock on wood) - i.e. internet is running smoothly, but pages load rather slowly (major lag), despite speedtest showing speeds are normal!!!

The only change since my issues yesterday:
1) I upgraded my router firmware (none of the changes in the latest two firmware revisions should have made any difference though)
2) Not using my laptop (since yesterday evening) to surf the web
3) Not accessing the SB8200 status page.
4) Not connected to my work network since yesterday evening (using Citrix receiver).

Speedtest speeds are fine this morning.
Web pages load relatively quickly but fail to completely load all content for a while (up to a minute). Something odd is still going on. :(
I disabled my firewall and that did not make a difference.

Also my two wifi thermostats are not re-connecting (in the past they would quickly reconnect to the network). They both say "no IP address". :(

I ruled out the router by connecting directly to my cable modem.

Edit - It is due to the modem or some signal / noise issues affecting the modem over time:Instantly after rebooting the cable modem (1 minute ago), web pages load lightning fast again. So it is definitely the modem OR something which impacts the modem after several hours and slows down internet sites...
Speedtest shows full speed however, which is odd.
Perhaps a DNS issue, but who knows.
All this started right after my SB8200 was switched to receiving D3.1 (i.e. blue light on for downstream).
Curious to see what others are experiencing with their SB8200 who were switched to D3.1.

Looks like I may have to sell my SB8200.
I may try to reactivate it.

Anyone have experience with BOTH the Arris SB8200 and Motorola MB8600?

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Sat, 22 Jul 2017 08:49:56 EDT
telcodad posted :
said by Achilles91:
said by Riusaki:
Where can I find a MoCA filter locally (not online)??
Not a common item in most retail stores. Your best bet truly is Amazon.
I wonder if you can pick them up at the Xfinity stores?

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Sat, 22 Jul 2017 01:16:14 EDT
Achilles91 posted : Not a common item in most retail stores. Your best bet truly is Amazon.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Fri, 21 Jul 2017 22:44:01 EDT
Riusaki posted : Where can I find a MoCA filter locally (not online)??

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Fri, 21 Jul 2017 21:52:04 EDT
mikev posted : I was going to wait a couple more days before posting this in case something changes, but since I posted it in the Arris forum, I'll also post it here now...

Next week Comcast will be changing the SB8200 diplexer setting back to 1.0 GHz, which should reduce the modem's sensitivity to MoCA signals. I was told that "After 7/26 if you reboot your SB8200 you should pick up the change."

I'll likely keep my MoCA filter on anyway, since there isn't one at the tap apparently... but others experiencing issues that might be MoCA related don't need to invest in a filter if you can tough it out for the next few days.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Fri, 21 Jul 2017 20:53:55 EDT
Riusaki posted : My SB8200 was having the same issues when D3.1 was active. If I powercycled a few times it would sometimes switch to 3.0 and remain stable.

I think the modem just doesn't play well with Comcast D3.1. Maybe a future firmware update will fix this. For now I am going to stick with the CM600 I got on Wednesday that has been nothing but rock solid with almost no correctables/uncorrectables.

I wonder if the CM1000 has any issues.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Fri, 21 Jul 2017 20:36:11 EDT
njweb posted :
said by mikev:
Comcast's current configuration for the SB8200 makes it very sensitive to RF signals in the MoCA frequencies (~1.2-1.3 GHz in this case). This has the consequence of creating both corrected and uncorrectable errors if there are strong MoCA signals present (like from X1 cable boxes), even though the DOCSIS signal levels are normal and well within specifications.

Unfortunately, this is the result of a solution to an issue with provisioning the SB8200 on certain CMTSes in use on Comcast's network in some areas. The problem CMTSes will be upgraded later this year, and at that point Comcast will be able to return the SB8200's configuration so that it won't be sensitive to those MoCA signals anymore.

In the meantime, a simple MoCA filter can significantly improve things, if you're looking for a quick fix without buying a new modem and returning the SB8200.
Thanks for the valuable post. I am having major internet connectivity issues with my SB8200 suddenly. 3 reboots needed today alone (every few hours performance degrades to the point where web sites do not load; right after rebooting they load lightning fast and speedtest shows 13 ms ping time and 211 Mbps down and 12 Mbps up which is more than my 200/10 plan).

Signals are within spec.
Downstream power ranges between 3.2 and 6.6 dBmV depending on the channel.
SNR is 40.1 to 42 dB on the 28 QAM256 channels; the 1 'Other' channel (not QAM256) has a SNR of 38.8.
Upstream power is between 44.5 and 46.8 dBmV depending on the channel.

Most likely this issue can be attributed to Comcast switching me over to D3.1 today (i.e. my SB8200 always had only green lights since I got it and I have had it before they came out to amazon - ordered it directly from Arris). However today I got the blue light on the downstream side.
Might have to rename it the blue light of death in my case...

I had 16 QAM256 downstream channels till today; as of this morning I now have 29 downstream channels (28 are QAM256 and 1 is of type 'Other'; the 'Other' has a small number of (just 91) corrected errors' since I factory / hard reset the modem today.

My SB8200 also runs hot.

Is the officially supported Motorola MB8600 a better bet? (it runs cooler for one thing and I assume it does not have the RF sensitivity issue of the SB8200 on some CMTSes).

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Fri, 21 Jul 2017 15:24:51 EDT
MarkC1024 posted : My modem doesn't seem to even let me make that change. It's purely a cosmetic element so no big deal.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Fri, 21 Jul 2017 10:16:53 EDT
Franken posted : If Comcast were to tease you, they could configure channel 1 to not be a primary channel. Then it would never be on top. :)

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Fri, 21 Jul 2017 08:43:04 EDT
halfband posted :
said by Riusaki:
Just made the change now. Does this somehow increase overall stability?
This simply tells the modem where to start looking for the channel that contains the configuration information to setup the remaining channels. If it is set to the correct frequency it can shorten the modem boot time since it does not have to search as many frequency bands looking for the right channel. If it is set to the wrong place it can increase boot time as the modem starts searching in the wrong place. Start Frequency has zero impact on stability or performance.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Fri, 21 Jul 2017 02:02:32 EDT
bandit8623 posted : We have way to many people that just want to refresh the modem page and see a number...

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Fri, 21 Jul 2017 01:13:07 EDT
Achilles91 posted : Your Upstream signal look better with the Netgear CM600.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 18:52:06 EDT
Franken posted : I just meant that it technically doesn't do anything to have them sorted like that. The modem just put the most important channel on top, the primary channel, where it receives all the control messages from the CMTS.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 17:21:05 EDT
Riusaki posted : Just made the change now. Does this somehow increase overall stability?

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 17:13:32 EDT
Devious posted :
said by Riusaki:
Do you recommend I do this?
Well it will not hurt anything but it is not mandatory.

I always let the modem fully sync then whatever frequency is the lowest I set that as the starting frequency.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 17:09:17 EDT
Riusaki posted : Do you recommend I do this?

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 14:37:04 EDT
Devious posted :
said by Franken:
Is that important to you? Just push the sort button. :)
Was that some kind of joke?

There is no sorting in the GUI by clicking on the heading Channel ID or Channel or anything else listed at the top.

Do you even have a CM600 or just assuming that is how you could do it?

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 13:33:43 EDT
kucharsk posted : Ooooh, if neighbors' MoCA signals are leaking onto the feeder lines, the Comcast crews need to nip that in the bud now.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 13:32:10 EDT
mikev posted : Well, there should be one on your main line coming to your house... that way MoCA signals from your X1's aren't received by other Comcast customers in your neighborhood. But it seems that having one on the modem itself is also a good idea because of its current sensitivity to MoCA signals.

I only have my modem on the line into my house, no other Comcast equipment, yet I was having issues because of neighbors' MoCA devices until I put the filter on my modem.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 13:02:26 EDT
Franken posted :
said by Devious:
then all the channels and channel ID's will line up 1-24
Is that important to you? Just push the sort button. :)

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 12:40:07 EDT
Devious posted : What I liked on the CM600 is you can set the starting frequency then all the channels and channel ID's will line up 1-24

Set it to the lowest locked channel which in your case is 507000000

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 11:55:21 EDT
neufuse posted : aw, comon I say Zoom is garbage because of their name and company logo! seriously though, some people rate products by things like this.........

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 10:39:06 EDT
MarkC1024 posted : So where should the MoCA be installed in this situation? I have one coming into my house, which then splits to a line that feeds my primary X1 and my SB8200 via another splitter. The other line coming into the house then runs to another "slave" X1 device in the basement.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 09:40:57 EDT
kucharsk posted :
said by Anon0e35c :
SB8200 is made by Zoom which is garbage
I also find it entertaining that Zoom's cable modems have engendered few to zero complaints and are somehow considered "garbage."

Why, because you don't like what their heat sinks look like?

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 09:02:17 EDT
Chris 313 posted : Nope. Try ARRIS. Zoom is the holder of the Motorola name and is the maker of the MB8600, not the SB8200, which is what ARRIS makes.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 08:47:03 EDT
anon posted : SB8200 is made by Zoom which is garbage

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 07:47:52 EDT
mikev posted : Comcast's current configuration for the SB8200 makes it very sensitive to RF signals in the MoCA frequencies (~1.2-1.3 GHz in this case). This has the consequence of creating both corrected and uncorrectable errors if there are strong MoCA signals present (like from X1 cable boxes), even though the DOCSIS signal levels are normal and well within specifications.

Unfortunately, this is the result of a solution to an issue with provisioning the SB8200 on certain CMTSes in use on Comcast's network in some areas. The problem CMTSes will be upgraded later this year, and at that point Comcast will be able to return the SB8200's configuration so that it won't be sensitive to those MoCA signals anymore.

In the meantime, a simple MoCA filter can significantly improve things, if you're looking for a quick fix without buying a new modem and returning the SB8200.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Thu, 20 Jul 2017 03:05:39 EDT
Riusaki posted : After a tech visit, the tech checked all the connections and everything was good until we isolated the modem and it was showing noise. I went ahead and bought a Netgear CM600 and everything has been fine so far.

The CM600 runs a lot cooler than the SB8200. Gonna get an RMA from Newegg and keep the CM600.

Barely any errors after hours of use, as opposed to the SB8200 that would give me massive amounts of Correctables every few minutes.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Wed, 19 Jul 2017 22:21:43 EDT
Achilles91 posted : Your Upstream power signals are out of spec per the ARRIS published documentation.
»arris.force.com/consumer ··· dArticle

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Wed, 19 Jul 2017 17:10:23 EDT
Franken posted : It's true that correctables don't need to be a problem in 3.1, but you still need to watch out for uncorrectables. If the number of uncorrectables is wast, it indicates that something could be better.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Wed, 19 Jul 2017 08:42:09 EDT
neufuse posted : the real issue with that channel is that it is OFDM for DOCSIS3.1 which these modems show having a large number of corrected/uncorrected errors... which isn't what it really means, there are other threads on this topic here also. the modem pages need to have a different section for OFDM and say what they really mean instead of fitting it into a table like they have now

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Tue, 18 Jul 2017 22:50:30 EDT
anon posted : your channel 159 which is 705mhz is in the LTE cell phone spectrum. keeo your cell phone away from your modem. tighten up all coax connections at modem, splitter, tv boxes if u have to prevent cell phone signal ingress.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Tue, 18 Jul 2017 17:41:38 EDT
Riusaki posted : My connection went down again just 10 minutes after a Comcast rep I was talking to in a chat session restarted the modem. Here is the Event Log entry.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Tue, 18 Jul 2017 17:05:08 EDT
Devious posted : What is in the event log when the disconnects happen?

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Tue, 18 Jul 2017 16:26:43 EDT
Riusaki posted : This one I just took right now about 20 mins from the one in the first post.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Tue, 18 Jul 2017 16:24:50 EDT
EG posted :
said by Riusaki:
Channel 159 and it has a huge number of Correctable and Uncorrectables.
FWIW, the amount of uncorrectables is not "huge" in comparison to the amount of correcteds. Of course it all depends on the total "uptime" of the modem before that screenshot was taken.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Tue, 18 Jul 2017 16:24:47 EDT
Riusaki posted : When I notice a disconnect, I check it and the SNR drops down to single digits.

Re: [Connectivity] SB8200 Signals. Is this normal or bad?

Tue, 18 Jul 2017 16:18:10 EDT
neufuse posted : channel 159 is an OFDM channel for DOCSIS 3.1 these channels being bonded across a wide range of frequencies will show large numbers of "errors" it's normal for OFDM channels

Your SNR on that channel is pretty good being 38+

[Connectivity] SB8200 Signals. Is this normal or bad?

Tue, 18 Jul 2017 16:06:48 EDT
Riusaki posted : Around July 17th I am now getting constant disconnects and usually happens out of nowhere and happen at any time. In looking at my signals I have noticed a Channel 159 and it has a huge number of Correctable and Uncorrectables.

Is something wrong with my line or modem?

SB8200 Signal