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Forum Discussion
RBR750 DHCP
I have an Orbi RBR760 connected to my cable modem, also Netgear. My network Gateway / DHCP is 10.0.0.x. Works as advertised, most of the time. However, I noticed a number of connected devices that...
Thanks for the replies
The Modem is a Nighthawk AX6 (CAX30). WIFI disabled (in all of the many places it shows up). I have tried to turn off the router mode, the Orbi end of things then stopped working. I had to factory reset the Nighthawk to get back online. It does have a 170.x.x.x ip address from my ISP. DHCP for the LAN is 192.168.1.x the scope allows for only two IP addresses. firmware v1.4.10.8
RBR750 is in Router mode. Firmware v4.6.5.14, one satellite. Used to have two, one refuses to do anything, so I unplugged / deleted it. DHCP scope is 10.0.0.2 - 10.0.0.77
When I look at attached devices there are 6 that have 192.168.2.x for an IP address, and to add to the mystery, they all work / internet / all good. They show a gateway of 192.168.1.1 ARP -a presents me with the Orbi MAC address.
What I do not have is the DHCP scope of 192.168.2.x configured on any device on the network. Even if I was, it shouldn't work. I used to be a Banyan / Cisco network engineer, so this bother me.
While my Bandwidth and connectivity with the Orbi has been great, I find them extra special flakey.. I had a firmware problem last winter and Supports only answer was to do a hard reset. If I can't run this down, I may have to put the Orbi stuff on craigs list and go purchase something better.
Wow. What a puzzle!
To recap:
- The CAX30 WAN port has a public IP address.
- The CAX30 LAN port has 192.168.1.1
- Nothing is connected directly to the CAX30 besides the RBR750.
- The RBR750 WAN port has IP 192.168.1.2
- The RBR750 LAN port is IP 10.0.0.1
- The RBR750 DHCP range is 10.0.0.2 - 10.0.0.77
- The router Attached Devices page shows devices with both 10.0.0.x and 192.168.2.x IP addresses.
- When you dump the entire ARP table on a PC, there are entries with both 10.0.0.x and 192.168.2.x IP addresses.
Can you share the type of devices that have 192.168.2.x IP addresses?
Is the Guest WiFi network enabled?
I think you nailed it.
While I just looked at the list of attached devices. What type of devices? My phone, one laptop, iPad, other assorted smart switches. they are ALL on the Guest network.
So I did a search for orbi rbr 750 Guest network IP range. Appears that the guest network is responsible for the 192.168.2.x ip range. Explains why the MAC address is the RBR 750, I should have noticed that. I was hyper focused on how that IP range would even work, it would appear Netgear does it in the background. But this makes me question what the heck else is it doing all on it's own?
No double NAT issues. Tracert PC-> Obri -> Cable Modem -> ISP - > destination
Thanks
GN defaults to 192.168.2.1
If you have the Orbi in AP mode then there wouldn't be a double NAT issue.
If you have the Orbi in router mode along with the CAX, this will be a double NAT issue.
costler wrote:
Appears that the guest network is responsible for the 192.168.2.x ip range. Explains why the MAC address is the RBR 750, I should have noticed that. I was hyper focused on how that IP range would even work, it would appear Netgear does it in the background.
This is one of the design changes Netgear made between the original Orbi and the AX series.
- The original Orbi had both primary and guest WiFi in the same IP subnet. This forced Netgear do track which devices were in the guest network in order to prevent them from accessing the primary network. (The original Orbi provided an option to allow devices on the guest network to interact with the primary network, or to prevent it.)
- On the AX series, Netgear put guest devices in a separate subnet, which made preventing interaction trivial.
I've always wondered what caused Netgear to pick 10.0.0.x for the Orbi LAN subnet when the WAN port was in 192.168.1.x
There were hundreds of 192.168.?? subnets to choose from.
One would think that when the primary subnet changed to 10.0.0.x, then the guest subnet also should have changed. But... oh, well.
On the topic of Double NAT. There are specific applications which a Double NAT will affect (port forwarding, some internet gaming, UPnP, etc.) Internet search will turn up examples, such as https://kb.netgear.com/30186/What-is-Double-NAT There are (literally) hundreds of thousands of customers who exist blissfully ignorant that they have a Double NAT. All those people who just take their new WiFi system out of the box, connect the Ethernet cable, and proceed to use it. (Google, Asus, Linksys, Netgear, eero... all brands and models).
As long as they do not run into one of those specific applications, they never know. As a test, I connected three routers in a row:
ISP modem ->to->router 1->to->router 2->to->router 3-> PC. Everything I tried on the PC worked fine: email, web browsing, video streaming, YouTube, It was a challenge, but I was even able to forward a port through all three routers to a server on the PC.
I noticed that there had not been a mention of the service you are using to connect to the internet.
There might be a fourth option.
I had double-NAT issues and while I could put the modem/router into bridge mode, I still wasn't pleased with the performance.
I have Fiber to the home (CenturyLink). So I had an Adtran ONT -> Zyxel C3000Z -> Orbit RBR750.
I found out the settings I needed from CenturyLink support (my PPPoE username/password and the VLAN tagging I required) and configured those on my Orbi RBR750 and returned the Zyxel C3000Z to CenturyLink. No need to lease the modem any more.
I don't know if this at all applies to your setup, but I wanted to post that there could be a fourth option (if ethernet handoff is provided from an ONT device that is not the Modem/router) if a similar setup.
