Orbi WiFi 7 RBE973
Reply

Re: Comcast/Nighthawk IP assignment conflict?

Flash7Gordon
Guide

Comcast/Nighthawk IP assignment conflict?

Hi,   I recently installed my new Nighthawk, I am impressed and it is working pretty well.   But I have a Comcast ISP and they give you a router as part of the cable modem.  That Router assigns 10.0.0.x as IP addresses.   I noticed the Nighthawk assigns the same 10.0.0.x IP addresses (my old linksys was completely different, 192.168.1.x).   So could one or the other of these routers clobber an IP that was already assigned by the other?

Message 1 of 10

Accepted Solutions
TheEther
Guru

Re: Comcast/Nighthawk IP assignment conflict?

AP Mode is not the default setting and I don't think the R7000 would have enabled it by itself.  You may have been asked during initial setup whether you wanted to set it up as an AP.

 

In any case, now that we've established that AP Mode is enabled, the R7000 is not acting as a DHCP server.  The R7000 will relay DHCP messages back and forth between attached clients and your Comcast router.

 

If you are not using the Comcast wireless network, then you should turn it off.  It'll free up the wireless channel plus remove one thing for people to hack.

View solution in original post

Message 8 of 10

All Replies
TheEther
Guru

Re: Comcast/Nighthawk IP assignment conflict?

Yes, it could. You will want to change one of the routers to use a different subnet.  The Nighthawk can normally detect the WAN subnet and adjust the LAN subnet to avoid the conflict, but it appears that this didn't work.  You could adjust the Nighthawk to use 192.168.1.X/255.255.255.0.

Message 2 of 10
Retired_Member
Not applicable

Re: Comcast/Nighthawk IP assignment conflict?

I believe "KISS" would apply here.....use comcast in bridge mode with netgear in router mode or comcast in router mode with netgear in AP mode.

 

 

Message 3 of 10
Flash7Gordon
Guide

Re: Comcast/Nighthawk IP assignment conflict?

I appreciate both of your replies and they are guiding my thinking in this matter.  But I wish to be a little contrary now.  I am looking at the comcast admin attached devices and the nighthawk admin attached devices and somehow they both seem to be able to see devices that are attached to the other router (my nighthawk can see the computers i have ethernet wire connected to the comcast router, which in my mind would be the "blind spot" if there was one).  So if they see those devices they can probably avoid assigning ip's on top of each other.  

Message 4 of 10
Retired_Member
Not applicable

Re: Comcast/Nighthawk IP assignment conflict?

You might want to read up on NAT Translation and DHCP.

 

Read This Before Commenting

Message 5 of 10
TheEther
Guru

Re: Comcast/Nighthawk IP assignment conflict?

Double NAT is certainly a concern but it's unrelated to the question at hand of the same subnet being used on the Internet and LAN ports of a router.  The latter is a no-no and will only lead to grief.  I believe @Flash7Gordon is either very lucky that an IP address collision hasn't happened or he has enabled AP Mode on the R7000.  If he has enabled AP Mode, then everything is ok because the router and DHCP server functionality are disabled.

 

@Flash7Gordon, do you have AP Mode enabled?

 

If AP Mode is disabled, then can you provide the IP address and subnet mask information from the Internet Setup AND the LAN Setup pages?  I'm very doubtful that the R7000 would permit the same subnet on both ports.

Message 6 of 10
Flash7Gordon
Guide

Re: Comcast/Nighthawk IP assignment conflict?

Ether, Ok, I'm looking at Advanced Settings -> Wireless AP it's a funny page and has a diagram at the top of it, not the normal place I would expect to see a parameter setting check box.  The box for "Enable AP Mode" is checked just above the diagram.  I didn't check that after the installation, it was either the defualt or the r7000 figured it out.  But I believe I have DHCP mode functionality on the r7000.   Lot's of wireless devices are connecting to the r7000 and it's giving them an ip address.    I know my mobile stuff ins't connecting to the comcast wireless because it has a long gory password and I can't figure out how to change it.  My r7000 is ethernet plugged into one of the 4 wired ethernet ports on the comcast router/surfboard.

Message 7 of 10
TheEther
Guru

Re: Comcast/Nighthawk IP assignment conflict?

AP Mode is not the default setting and I don't think the R7000 would have enabled it by itself.  You may have been asked during initial setup whether you wanted to set it up as an AP.

 

In any case, now that we've established that AP Mode is enabled, the R7000 is not acting as a DHCP server.  The R7000 will relay DHCP messages back and forth between attached clients and your Comcast router.

 

If you are not using the Comcast wireless network, then you should turn it off.  It'll free up the wireless channel plus remove one thing for people to hack.

Message 8 of 10
Flash7Gordon
Guide

Re: Comcast/Nighthawk IP assignment conflict?

Thanks, so I can keep operating like I am and I will never get a conflict, right?  The r7000 isn't doing dhcp, but it's passing those requests to the comcast router and keeping track of them.   I'm marking your prior post as the solution.

Message 9 of 10
TheEther
Guru

Re: Comcast/Nighthawk IP assignment conflict?

Yes, to all your questions.

Message 10 of 10
Top Contributors
Discussion stats
  • 9 replies
  • 9301 views
  • 0 kudos
  • 3 in conversation
Announcements

Orbi 770 Series