CM 1100 no longer xFinity Compatible

[Tucson_Jim]

The CM 1100 cable modem is no longer compatible to use with xFinity.

They can no longer see or talk to the modem. On their webpage they show INCOMPATIBLE BASED ON FILTERS. Customer service confirmed they cannot see nor talk to the modem.

Have no idea what this means nor how to resolve this.

Looks like time to buy another cable modem that IS on the xFinity list. May NOT be NetGear if this is not solvable.

Since xFinity cannot update the cable modem, is netgear now responsible to resolve this? the CM 1100 is still being sold as xFinity compatible. Not even sure how to update modem to resolve this if there is a solution.

[FURRYe38 · Accepted solution]

The the CM has LAG support, base speed support is for 1Gb and in most cases home users don't use LAG. Even the WAN ports are only rated at 1Gb per port so technically, the CM1100 reaches this limit on a  single 1Gb line. 

We know the ISP recently split there speed tier last year, now 800Mpbs and 1.2Gb. Were seeing problems with some other modems that only support 1Gb on the WAN and LAN side and the ISP up'd the speed to 1.2Gb. The ISP has not certified these modems for 1.2Gb services. So this change is on the ISP side. 

One thing to try, have the ISP set your speed package at 800Mpbs. 

Another would be to test the CM1100 at a different location, friends or family that may have a different ISP service or speed tier and see if the modem responds differently there. 

Or find something that handles 1.2Gb or higher speeds. NG CM2000 series comes to mind since those have 2.5Gb WAN port.

[FURRYe38]

Should be compatible. 

Possible something happening between the ISP service and the modem.

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-m...
https://kb.netgear.com/30008/How-do-I-view-or-clear-the-event-logs-on-my-NETGEAR-cable-modem-or-mode...

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?

Try a factory reset on the modem by pressing the reset button for 10 seconds then release. 

Be sure to power OFF the modem for 1 minute then back ON.

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.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...
https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html

Can you try a different modem to see if something else works or sees a problem? 

[Tucson_Jim]

No Joy on any of that. xFinity says not compatible based on filters. Need to know what that means & how to resolve. This is a Netgear issue. xFinity cannot see or talk to modem like it was able to do in the past.

Cannot access modem through router (another Netgear RAX 78 product). Cannot access modem directly.

[FURRYe38]

So with the modem disconnected from the ISP coax line and pressing the reset button then release and connecting one wired PC to the back of the modem with out the RAX router connected, you can't access the modem at 192.168.100.1 at all after 2-3 minutes? 

[plemans]

Their list is screwed up. reason why is it used to be they pushed 1gig service and it was compatible. But when they bumped it to 1.2gig service, suddenly everything that only had a gigabit port was "incompatible". Even through it has 2x gigabit ports and supports wan port aggregation. Its a change in how they determine compatible. Not something netgear did. Its just comcast trying to get more $ out of people or switching to their services. 

If you drop your filter down to the 800mbps service, its compatible (I checked on my xfinity). 

Netgear can't control what xfinity or any ISP sets for their compatible list. 

but it should still work fine. 

So if its not, it could either be a line issue or a modem issue. 

Are you able to log into the cm1100 and check its cable connections page and event logs?

[FURRYe38]

Also still on this list that reports the CM being approved for use:

https://approvedmodemlist.com/comcast-xfinity-approved-modems/#modemlist

[Tucson_Jim]

Thanks for the reply.

If you drop your filter down to the 800mbps service, its compatible (I checked on my xfinity). Not sure I would want tjis as I am paying for the higher Gig service & have daughter working from home.

Netgear can't control what xfinity or any ISP sets for their compatible list. Understand

but it should still work fine. Does work fine but xfinity upgrades not longer possible

So if its not, it could either be a line issue or a modem issue. 

Are you able to log into the cm1100 and check its cable connections page and event logs? Cannot log into modem, not even sure how to do that.

Might have to bite the bullet & replace modem to get the gigs I am paying for. Looking at Arris S33

J

[FURRYe38 · Accepted solution]

The the CM has LAG support, base speed support is for 1Gb and in most cases home users don't use LAG. Even the WAN ports are only rated at 1Gb per port so technically, the CM1100 reaches this limit on a  single 1Gb line. 

We know the ISP recently split there speed tier last year, now 800Mpbs and 1.2Gb. Were seeing problems with some other modems that only support 1Gb on the WAN and LAN side and the ISP up'd the speed to 1.2Gb. The ISP has not certified these modems for 1.2Gb services. So this change is on the ISP side. 

One thing to try, have the ISP set your speed package at 800Mpbs. 

Another would be to test the CM1100 at a different location, friends or family that may have a different ISP service or speed tier and see if the modem responds differently there. 

Or find something that handles 1.2Gb or higher speeds. NG CM2000 series comes to mind since those have 2.5Gb WAN port.

[Tucson_Jim]

OK, need to try that

thanks