Router doesn't see cable modem

[DavePlumb]

I've been using my R6400v2 for 6 months now - working fine.

I just swiched from an xFinity Cable modem to an Arris Surfboard SB8200

The cable model is connected to to Internet (I'm typing this hard-wired)

But I can't connect the Router to the modem

I have the yellow ethernet cable goint from the modem to the yellow port on the router

I can connect hard-wired to the router and everything looks correct, but when I login to the router, it shows

Internet Not Connected.

I've done the usual reboots/resets to no avail

I've even tried Restore Factory Settings

I've also tried all of the options in the Setup Wizard (power cycle, re-conncect cable) & I just get

 "Problem Detecting the Internet Connection"

I've even tried typing in the modem's MAC address - nothing

If I unplug the ethernet cable, the "Internet" light on the modem goes out, but when I plug it back in. it immediately turns amber

The modem ethernet port light to the router is green and flashes like its communicating,

the router internet light is amber and flashes slowly

Anyone have a clue?

[plemans · Accepted solution]

The SB8200 has 2x ethernet ports on the back. But only 1 device can be plugged into it for most ISPs. 

So make sure that when you're going through setup that nothing else is plugged in. 

Try this. 

Turn off the modem and router and unplug all devices (including coax) from both. 

Connect the coax back to modem and turn it on/plug it in. give it serveral minutes. 

Then connect port 1 from modem to wan port on router. 

Turn on router. give it several minutes. 

Attempt setup on router

[plemans · Accepted solution]

The SB8200 has 2x ethernet ports on the back. But only 1 device can be plugged into it for most ISPs. 

So make sure that when you're going through setup that nothing else is plugged in. 

Try this. 

Turn off the modem and router and unplug all devices (including coax) from both. 

Connect the coax back to modem and turn it on/plug it in. give it serveral minutes. 

Then connect port 1 from modem to wan port on router. 

Turn on router. give it several minutes. 

Attempt setup on router

[DavePlumb]

Thank you, plemans. That was, indeed the problem.

I only wish I had waited to see your answer.

I ended up spending over an hour (and $90 for a Support Contract) with a very helpful Netgear Support tech.

After many, many re-configs and re-boots, she finally had me disconnect the second cable from the SB8200

So it wasn't a Netgear problem after all.

I am NOT HAPPY that Arris does not mention th fact that you can't have two cables plugged in anywhere in their setup instructions.

After much research I understand what the two ports do, but Arris should make that VERY obvious in their instructions.

There are two Ethernet ports in the SB8200, why would I think I can't use them both at the same time.

[plemans]

Sorry it cost  $90!  But I'm glad to hear you got it working. 

It is unfortunate that there isn't better education on the 2-4 port modems on the fact that for the average consumer, you can't use the extra ports. The higher end routers (with wan port aggregation) can, business class custumers, and some rare isps.