Question Netgear CM3000/Linksys Wireless

[William.Doyle]

Good morning. I had to update my Comcast modem because of technology changes (the speeds are now incredible, eye popping even). Since I don't like to rent equipment, I bought a modem from Comcast's compatible hardware list. It's a good modem it appears. However, I could not get the modem to work with my wireless router. The modem does not have a built in radio (mistake on my part). The modem, a Netgear CM3000 had what I thought were Ethernet ports on the back. I looked no further than that (another mistake). The ports are not really Ethernet ports but link aggregation ports? Never heard of it. They were initially off, I turned them on. The Linksys Atlas WiFi 6E Home WiFi Mesh router kept saying I wasn't connected to the internet port. I wiped it and started from scratch, same thing. Said I was connected without internet. After two hours or so, I gave up. Good thing I bought a separate Verizon wireless as a backup so my wife could work. I'd be in the dog house. So having said all that, what the hell am I doing wrong? I hate the chuck the router its only a couple of years old. Thanks much

 

[cruisetung]

Don't think you bought the wrong one.

However I wonder if you have given the MAC address of the Netgear CM3000 modem to Comcast for activation, if not, you will not have internet. All cable ISPs require you to give them the mac address of the modem, no exceptions.

First, there is no ethernet connection on the WAN (internet) side for all cable modems, just coaxial connection, no matter what brands or models.

Second, there are 3 LAN ethernet ports on Nergear CM3000 modem - one 2.5G and two 1G. Link aggregation feature supports for those two 1G ports means that if you turn the feature function on then you can combine these two 1G ports and create a 2G channel.

So let's say you have a PC with 2 1G ports, in theory you can connect two ethernet cables to the modem's aggregation ports and transmit data on 2G speed.

 

[William.Doyle]

I connected the modems fast port (I forget what it is called) to the 5gbs port on the router and nothing doing. I tried a lot of different combinations of cables in different ports and nothing worked. I know I am missing something but I never ran into this problem before. I think the router use the same LAN IP as well. Which makes everything else moot. The speeds I am getting are fantastic really, it is just the download speeds that are pathetic and worse than what I had previously. One of the download channels is blocked. I am at work right now, I'll give it another go tonight.

 

[Ralston18]

Get a sense of the proverbial "big picture".

This Netgear modem?

https://www.downloads.netgear.com/files/GDC/CM3000/CM3000_IG_EN.pdf

This Linksys Atlas router?

https://downloads.linksys.com/support/assets/userguide/MX8500_USERGUIDE_EN.pdf

Connectivity being something like the following line diagram ( where ----> represents an Ethernet cable):

ISP (Comcast) === (coax cable) === > [Port ?] CM3000 [LAN port ? ] ----> [Internet port] Atlas Wifi 6e [LAN port(s)] ----> wired network devices and ~~~~> wireless network devices.

Feel free to edit and correct my line diagram. Identify and lable the connected ports as referenced or identified in the linked User Guides. Post your diagram. You can copy and paste the bold text above and edit/update as necessary.

CM3000 should have its' DHCP (router) functions disabled. Only the Atlas router should be providing DHCP IP addresses.

Run "ipconfig /all" (without quotes) via the Command Prompt on a network computer. Post the full results.

You should be able to copy and paste "ipconfig" without needing to retype everything.

Redact personal name if shown, and the network name if revealing.

NOTE: The only IP address of concern is the IP address that Comcast (Xfinity) has provided to your modem/router. That address can be found via "What is my IP".

One issue can be that Linksys is "forcing" you to access the router via Linksys' website. It can get very confusing between logging into your Linksys account and then having Linksys account go back and access the router. All the more so if the modem is also playing "router".

You should be able to log into the router directly by using your browser to enter the router's IP address directly. You will need to have the router's login account name and password. The default IP likely being 192.168.0.1 or 192.168.1.1. If you have not changed the default IP.

 

[bill001g]

Start with the simple things first. Cable modems tend to lock onto the first mac address they see. If there are multiple ports sometime it will only use the first one.

So I would go back in and turn off the 2 lan aggregations ports since very few routers support this. Now unplug the router from the modem. Power cycle the modem and wait until the lights indicate that it is connected. Now plug the 2.5g port on your router into the 5g port on the modem.

In theory the modem should now give the router a IP address. If you log into the router and it does not have a IP on its wan port I would then be suspect that the ISP messed up and did not properly activate the modem on their network. A modem will completely connect and appear to function it just never gets any IP addresses when it is not activated to a account.

 

[William.Doyle]

Thank you guys, I always come here when I have something unsolvable. I am going to be playing with this tonight (the modem/router that is) LoL. I have to make it work. The weird thing, when I enable/disable port aggregation I lose my connection and have to reboot everything.

 

[William.Doyle]

Alrighty, here we go. This is the same thing I did the other day and it didn't work so don't ask me why it works now. The wireless works which is the most important thing for my wife however, since I am connected via the slower ports now, the speeds are terrible. Uploads speeds are unaffected download are awful. The ports in the back of the modem still don't work but the ones on the router do although with terrible throughput. I connected the high speed port from the modem to the router using the ports on the router for my PC. I can't do much in the modem there aren't a lot of options in there. The router isn't much better.

 

[Ralston18]

"I connected the high speed port from the modem to the router using the ports on the router for my PC."

What cables are you using? Source?

 

[William.Doyle]

"I connected the high speed port from the modem to the router using the ports on the router for my PC."

What cables are you using? Source?

They are Cat 6 cables. Is that what you are asking?

 

[William.Doyle]

Only one of the upstream channels is locked.

 

[Ralston18]

Cables - yes.

Cat 5e or 6a, round, copper, AWG 22-24.

Not flat, copper clad aluminum, thinner AWG. Not Cat 7 or 8 of any sort.

Lots of fake cables out there.

If possible, swap in some other known working (at speed) cables just as a matter of elimination.

Does not take much to cause connectivity problems. A cable can work well on one connection path and not so well on another. Just the way the terminations are made and how well it all fits: plugs and ports.

Another place for problems is if the house is wired for Ethernet: in-wall cables, wall jacks/ports.

 

[cruisetung]

As suggested by @bill001g , you should disable port aggregation feature of the modem, connect CM3000's 2.5G port to Linksys router's (this one?) multigig internet port, don't link anything else to the other two aggregation ports.

Please take a screenshot of the modem downstream/upstream channels and post it to imgur.com

You might also want to make a call to Comcast.