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Why would SB6190 fail to aquire bonded upstream channels?

  • 28 April 2023
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I have been using the SB6190 for over 7 years, and was getting expected performance with Comcast Xfinity until about 1 year ago.  As WIFI with my Netgear R7900 seemed to have dropped, I replaced it with Netgear Model RAX54S-100NAS. WIFI improved significantly, but my download speed over ethernet jumped from 182 Mbps to 483 Mbps and upload speed came back to 12 Mbps from 6.0 Mbps! Great, I thought, until intermittent connection issues started to occur. 

Because TV box service was affected, I blamed the ISP during the first outage. Troubleshooting connections to a booster module and splitters did not pan out, but service returned for a day. But the problem recurred. I took out the booster and had been running the modem with 15 dB less input signal power; that seemed okay with 256QAM channel powers ranging between -6.2 dBmV and -4.0 dBmV, and correcteds  and uncorrectables all 0 or very low. Five bonded ATDMA upstream channels were available.

Another day passed with internet available until 8:18 PM tonight. The modem appeared to have rebooted or reset after the first of three events (descriptions provided):

Received Response to Broadcast Maintenance Request, But no Unicast
Maintenance opportunities received - T4 time out;CMMAC=
**:**:**:**:**:** ;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1 ;CMVER=3.0;
No Ranging Response received - T3 time-out;CMMAC=
**:**:**:**:**:** ;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1 ;CMVER=3.0;
Received Response to Broadcast Maintenance Request, But no Unicast
Maintenance opportunities received - T4 time out;CMMAC=
**:**:**:**:**:** ;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1 ;CMVER=3.0;.

The modem status showed no bonded downstream or upstream channels. I selected the Reboot button in the Web Manager Configuration tab, to no avail. I physically pulled the plug on the modem to force the hardware reboot, and the indicator lights marched to all on; however, the send channel light did not change from green to blue. Internet service to the modem was back, with 32 bonded downstream  channels but only one upstream channel. That yields the 480 Mbps download speed accompanied by the usual 12 Mbps upload speed allotted to my account.

This last outage did not affect operations of set top boxes, as forward and backchannel service to them was demonstrably present. So the question arises whether hardware faults are occurring in my SB6190, or if modem provisioning by Comcast Xfinity might be at issue? 

Comments and advice would be appreciated. 

(edit: CMMAC information removed)

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Best answer by SURFboard Moderator 24 May 2023, 02:00

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8 replies

L
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I would suspect modem provisioning only from my experience with Cox.  I had exactly the same issue (without getting a new router which isn’t related of course)  They kept blaming my sb6190 which is the easiest thing for a cable connection guy/gal to do.  I looked at the logs, printed out my signal strength and compared it to specs and pointed out the deficiencies.  They basically responded with they can’t match all cable modem specs and the manufacturer’s specs are fairytale specs that can’t be achieved at all times.  A couple of months later, they had maintenance in my area and the problem disappeared.  I guess my point is to not let the ISP make you doubt yourself or your sb6190.  =)

plemans
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When you’re having issues, get a screen snip of the cable connections page and event logs (not just a couple of them) and post them back here. Your initial ones look like line issues. And its not uncommon for line issues to be intermittent. 

Current setup: Netgear CM3000-->Netgear RBE973S-->2.5gig tp-link switch, Xfinity 1.4gig/240mbps
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Status and Log pages follow:

 

(edit: image with CM-MAC information removed by the moderator)

Status as of 2023_0428 9:19 p.m.

 

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Here is a prior status page from 2023_0425 showing upstream bonded channels present. The boost amplifier was removed at this time, and currently remains out of the network.

Status on 2023_0425 

 

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Further development. I decided to try resetting the router and the modem. First, I powered down the router, then I unplugged power to the modem. After 30 seconds, I powered up the modem and watched the sequencing of status lights; they all came on and the downstream and upstream lights came on blue, indicating bonded channels aquired. Then I turned on the router, and could verify the presence of the bonded channels by logging onto the modem. Here follows the status and log pages:

Status page, upstream bonded channels present 

(edit: images with CM-MAC information removed by the moderator)

 

I do not understand why so few events appear in the Log. Only one priority 6 event occurred after power cycling of the modem. And now the upstream bonded channels are present. Explanations would be appreciated.

S
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Hello CMN_SBC

                             The logs are Values read by technicians from the internet provider end, since the logs are what the coaxial cable transmits and the log screen on the router is the translator so can be easily read by them, the coaxial cable is owned by the Internet service provider, I wouldn't be able to tell you what that means.

                           If your Event Log is reporting a high volume of errors, this would indicate a potential CMTS signal issue. To troubleshoot these errors, we would like to note the current signal levels being used by your SB6190. You an check on the modem signal level mentioned on the article below whether you can see for the acceptable levels of the interface 

                       http://arris.force.com/consumers/articles/General_FAQs/SB6190-Cable-Signal-Levels

If the values are not in acceptable range that needs to be corrected by the internet service provider. Let us know if this helps.

 

                    

SURFboard Community Moderator Team
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A few months ago, my SB6820 was encountering excessive errors and at one point repeatedly failed to acquire bonded upstream channels. See 

https://community.surfboard.com/members/lareman-823 commented that he had the same issue and that with his ISP  later doing “... maintenance in my area and the problem disappeared.” 

Out of frustration, I reluctantly scheduled a maintenance visit with Comcast, and required the technician to verify signals at the cable drop. Bottom line was a defective cable, which the technician claimed has a solid sheath that frequently fails under mechanical stressing.  He further stated that Comcast has been routinely replacing this type of cable “whenever they find it.” 

Needless to say, download speed jumped from 180 Mbps to 480 Mbps and incidences of errors fell tremendously. The technician’s test equipment showed excellent signal characteristics achieved after the replaced the cable drop.

My cited posting had been closed to comments without a solution. https://community.surfboard.com/members/surfboard-moderator-593 at the end stated that if signal levels “...are not in acceptable range that needs to be corrected by the internet service provider.” The signal levels were actually in the acceptable range; however, performance was impacted by apparent signal gaps attributed to the defective cable drop.

The problem is truly solved.

S
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A few months ago, my SB6820 was encountering excessive errors and at one point repeatedly failed to acquire bonded upstream channels. See 

https://community.surfboard.com/members/lareman-823 commented that he had the same issue and that with his ISP  later doing “... maintenance in my area and the problem disappeared.” 

Out of frustration, I reluctantly scheduled a maintenance visit with Comcast, and required the technician to verify signals at the cable drop. Bottom line was a defective cable, which the technician claimed has a solid sheath that frequently fails under mechanical stressing.  He further stated that Comcast has been routinely replacing this type of cable “whenever they find it.” 

Needless to say, download speed jumped from 180 Mbps to 480 Mbps and incidences of errors fell tremendously. The technician’s test equipment showed excellent signal characteristics achieved after the replaced the cable drop.

My cited posting had been closed to comments without a solution. https://community.surfboard.com/members/surfboard-moderator-593 at the end stated that if signal levels “...are not in acceptable range that needs to be corrected by the internet service provider.” The signal levels were actually in the acceptable range; however, performance was impacted by apparent signal gaps attributed to the defective cable drop.

The problem is truly solved.

 

Hello @CMN_SBC

We moved your post to the original topic and opened this topic for further discussion.

SURFboard Support Team

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