CM1100 No Longer Compatible with Xfinity Due to Security Software

What Firmware version is currently loaded?
Please post a copy and paste of the modems connection status and event log page.
https://kb.netgear.com/30007/How-do-I-obtain-the-cable-connection-information-from-a-NETGEAR-cable-modem-modem-router
https://kb.netgear.com/30008/How-do-I-view-or-clear-the-event-logs-on-my-NETGEAR-cable-modem-or-modem-router

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Marty1330 wrote:

Hello.  I too have a CM1100 connected to Comcast/Xfinity "Superfast" (800Mbps) internet.  We received an email from Xfinity on 3/14 informing us that our internet speed had been increased (to 800Mbps) and that our "internet equipment is not able to deliver these new speeds."  AFAIK, the CM1100 is completely capable of handling sub-gig speeds (even greater!).

 

Perhaps not so coincidentally, around that timeframe it seems that we started to experience frequent network performance notifications from our streaming devices (e.g., FireTV) and my video conference calls have been regularly freezing or even dropping due to lost WiFi connection.  I was thinking it was our router (Linksys EA8300), but last night we lost internet at the CM1100 and couldn't get it back until I swapped it out for previous modem (SB6141).  The internet connection has been stable since.

 

I began to research issues with the CM1100 and that lead me to this thread.  The indicators on the CM1100 appear to be normal, but I will admit that I didn't inspect the logs prior to swapping it out.  Has Xfinity/Comcast done something to impact the operation or compatibility of the CM1100 with their network?  Does it need a FW update?  If so, how do I get it if it won't even connect to their network?

 

My CM1100 has only been in service 15-16 months and all visual indications are that it's still operational.  I dread trying to troubleshoot this with Comcast support.  Can anyone on this thread help (I'm looking at you DarrenM 😉)?

 

Thanks in advance for any assistance or guidance you can offer.

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Hi FURRYe38.  Thanks for your reply.

As I recall, the FW was v1.0 and the last time I checked (months ago) there wasn't an update available.  I heard that the modem FW was controlled by Comcast, not the modem manufacturer.

I'll have to take down my network to swap in the CM1100 and then call Comcast to re-authorize it (I think).  Will have to wait for some down-time around the house.  You'll know better than me, but I suspect that the modem will clear the event log after it boots.

Ya, give the modem 10-15 minutes of being online then collect the logs. 

Be aware that CC and XF changed there speed tier plans last year. They seem to have removed the 1Gb plan and split into a 800Mpbs and 1.2Gb plan. I know that some areas still have the 1Gb service. I presume eventually the ISP will phase that out nation wide. The CM won't support the 1.2Gb tier. 800Mpbs is well supported  though. 

I have been carefully watching and tracking my speeds ever since doing the original post.  The speeds do seem to bounce around more, but so far I have not had issues with things dropping or freezing.  At times I am even now seeing speeds over 800Mbps.   Every now and then I do still get the Xfinity No Longer Compatible with Xfinity email followed next day or two with a new hardware offer.  

I checked my CM1100 modem...

Was anyone from Netgear able to get information from Xfinity?   Basically... do I need to start worrying again or am I okay until DOCSIS 3.1 is no longer supported?

I did check my Event log and only had 1 day in last two months that had  a few events.. though it may be the day Xfinity truck stopped at the main box on road and my modem went down and then back up just before they left:... though there is a later time too... any concerns?:

Any insights to what these mean would really be appreciated!

Please post a copy and paste of the modems full connection status page.
https://kb.netgear.com/30007/How-do-I-obtain-the-cable-connection-information-from-a-NETGEAR-cable-modem-modem-router

I see Criticals that the ISP needs to review and resolve. Any Errors or warnings should be reviewed as well. 

https://highspeed.tips/docsis-events/

Will know more as well after you post the cable connections status page info here.

FURRYe38 

Attached is the latest Cable Connections page..

Ok, power levels are with in spec:

https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router

I see some Correctables however there not bad. Should be mostly zero so there is some minor line issue seems like.

Be sure your using a good quality LAN cable between the modem and router. CAT6 is recommended. 
What is the brand and model of the host wifi router connected to the modem?

Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly.
Be sure there are no coax cable line splitters in the between the modem and ISP service box. 
Be sure your using good quality RG6 coax cable up to the modem. 
Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.
Be sure to power OFF the modem for 1 minute then back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Modems/m-p/1530376#M12853
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html

Unless the ISP is pushing to the 1.2Gb plan which the CM wouldn't fully support, 1Gb or lower speed tier should work with the CM modem. I know that XF seemed to have removed the 1Gb tier from some areas of service and are now pushing a 800Mpbs and 1.2Gb tiers. 800Mbps should be compatible and supported by the ISP unless they are not supporting any DOCSIS 3.1 modems which I highly doubt. There marketing dept I persume would be giving false information or pushing users to use higher speed teirs when they don't really need too. 

FURRYe38 

Router TP-Link AX3200 Tri-Band

The link to provide insights to event log was helpful, but not sure I fully understand exactly what these are and what causes them:

- UCD invalid or channel unusable

- Started Unicast Maintenance Ranging - No Response received - T3 time-out

- Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time

Would these occur if Xfinity had disconnected temporarily out at the main box?

Most definitely. Most items seen in the event logs are on the modem side so ISP should know about all those and how to resolve them. 

 Marty1330

 Marty... hopefully all went okay swapping the modem back in.   I will be really curious what sort of insights can be gained.  My fingers are crossed we don't find out something that eventually will impact all the CM1100 modems.   As said above... so far mine is ok.

Did you make contact with the forum moderator that asked you to PM him some ISP account info?