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CM1200 DHCP fails after ISP connection established

ScottJacob
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CM1200 DHCP fails after ISP connection established

New CM1200. Power CM on and a connected laptop gets an IP address, allowing browser to access cable modem web adminstration. Connected to ISP (WOW) and they activated from their side. As soon as they brought cable modem connection up, the ethernet ports stopped serving DHCP so no devices could access anything. Power cycle CM and while it is establishing ISP connection the CM serves DHCP but as soon as connection to ISP completes the CM stops serving DHCP again. ISP says Netgear has to change the configuration but it seems more like the ISP is pushing a configuration to cable modem that changes its behavior. Thoughts?

 

Model: CM1200|Nighthawk Multi-Gig Speed Cable Modem
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plemans
Guru

Re: CM1200 DHCP fails after ISP connection established

the mistake a lot of people make is thinking that the cm1200 can have mulitple devices connected to it because it has 4 ports. The only way to connect more than 1 devices to it is if its a business class line or if your isp supports multiple public ip addresses for free (wow doesn't). 

So try this. 

Power off the cm1200. disconnect everything from it including the coax. 

Power off your router. wait a couple minutes. 

connect coax back to cm1200. power it on. give it a couple minutes. 

Connect port 1 of the cm1200 to the router's wan port. 

Power the router on. give it a couple minutes. 

attempt setup/using the router. 

 

make sure to plug nothing else into the cm1200. Again, only 1 device can be connected to it. You can run wan port aggregation on it if your router supports it but I haven't heard a good thing about wan port aggregation on consumer routers. 

CM2000-> RAXE500-> GS716v2-> WAX218-> EX8000

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Message 2 of 2

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plemans
Guru

Re: CM1200 DHCP fails after ISP connection established

the mistake a lot of people make is thinking that the cm1200 can have mulitple devices connected to it because it has 4 ports. The only way to connect more than 1 devices to it is if its a business class line or if your isp supports multiple public ip addresses for free (wow doesn't). 

So try this. 

Power off the cm1200. disconnect everything from it including the coax. 

Power off your router. wait a couple minutes. 

connect coax back to cm1200. power it on. give it a couple minutes. 

Connect port 1 of the cm1200 to the router's wan port. 

Power the router on. give it a couple minutes. 

attempt setup/using the router. 

 

make sure to plug nothing else into the cm1200. Again, only 1 device can be connected to it. You can run wan port aggregation on it if your router supports it but I haven't heard a good thing about wan port aggregation on consumer routers. 

CM2000-> RAXE500-> GS716v2-> WAX218-> EX8000

View solution in original post

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