Network Setup with Multiple Routers on LAN as well as Orbi on LAN

[heathergillette]

Hi Everyone, I've diagramed my network configuration showing multiple routers connected via LAN, and on all routers (other than the main) I have DHCP disabled and static IP addresses.  One of these routers is an Orbi, but on this one I didn't disable the DHCP because when I do, I can't connect to the Orbi management console again.  But, because the Orbi has DHCP enabled, I believe it is causing IP conflicts, because about once a week, the internet is no longer being received at all of the accessory routers, while there is still internet available at the main router.  I'm looking for advice on how to configure the ORBI as I believe I have everything else correct.

I can't seem to upload an image to this forum post. The screen shot of my network configuration is here:

https://drive.google.com/file/d/1yrLWbondSQX9bqspG57P0T8jPPLXKI43/view?usp=share_link

Thanks for the help!

Heather

[CrimpOn · Accepted solution]

It is probably irrelevant, but the conventional way to manage a situation like this is to put all of the secondary routers into Access Point (AP) mode so that there is one big LAN IP space managed by the primary router.  With each of these devices in 'router mode', they will all have internet access, but communication between devices may be blocked.

[CrimpOn]

Page 71 of the User Manual describes how to disable DHCP on the Orbi router:

https://www.downloads.netgear.com/files/GDC/RBK50/Orbi_UM_EN.pdf 

I believe the issue is not DHCP, but the fact that the Orbi is in router mode.

Orbi routers have a quirk that they automatically create an IP subnet that is different from the IP subnet that their WAN port is part of.  So, when the router is assigned 192.168.1.5 by the upstream router, the typical behavior is to create a LAN subnet of 10.0.0.x.

Can you please report two items:

• What does the Advanced Tab,Setup, LAN Setup page report as the IP address and subnet mask of the router?
  (on the far right hand side of the page)  Here is mine:
  
• When devices are connected to the Orbi system, what IP addresses do they receive?
  Are they in the 192.168.1.x subnet or the 10.0.0.x subnet?

When in router mode, the Orbi typically does not respond to connections from the WAN port.  Thus the Orbi web interface is not normally available from the WAN side. Only from the LAN side.

[heathergillette]

Hi thanks so much for the help!

Here's what the advanced LAN settings show (see attached screenshot).

And the answer to this question "When devices are connected to the Orbi system, what IP addresses do they receive?
Are they in the 192.168.1.x subnet or the 10.0.0.x subnet?" They are being given the subnet as 10.0.0.x, yes.

[CrimpOn]

Thanks for the confirmation.  With the Orbi in router mode and performing DHCP, every device connected to the Orbi system is hidden by Network Address Translation and appears to be 192.168.1.5 to the outside world. NAT maintains internal tables which translate the IP ports used by these devices into artificial IP ports seen by the outside.  There is (literally) no way that the Orbi can cause any kind of IP conflict.

When connecting to the Orbi management interface it would be useful to know

• Where is the connection device connected?
  To the Orbi system LAN side?
  To the primary router? (The Orbi WAN side)
• What IP address is used to reach the Orbi?

It would also be fascinating to know what happens when the Orbi DHCP function is disabled.

i.e. what IP addresses do all the devices connected to the Orbi receive?

(I have never attempted this combination myself and wonder if devices connected to the Orbi receive IPs in the 192.168.1.x subnet and what Gateway IP address they are told to use.)

[heathergillette]

You have been so incredibly helpful, thank you.  I don't think I will disable DHCP given your reassurance, but if I do go down that road to experiment more, I will let you know what happens to all of the other connected devices!

I am going to take a look at each of the accessory routers (other than the orbi), and see what I've done wrong there as something is happening somewhere to cause conflict, but only on occasion.

Thank you again!

Heather

[CrimpOn · Accepted solution]

It is probably irrelevant, but the conventional way to manage a situation like this is to put all of the secondary routers into Access Point (AP) mode so that there is one big LAN IP space managed by the primary router.  With each of these devices in 'router mode', they will all have internet access, but communication between devices may be blocked.

[heathergillette]

Ok, even though they are daisy chained to each other, and not each directly connecting to the home/main/first router?

[CrimpOn]

My understanding is, "yes".  When a device on the farthest router broadcasts a request for an IP address, that broadcast will be repeated (out every port - it is a broadcast packet) and out the WAN port up the line until it reaches a DHCP server somewhere on the network that responds with an IP assignment.

If it is working now, I see no urgency in terms of changing everything.

[heathergillette]

Got it.  Super helpful again!  I have had trouble, which I thought was due to IP conflicts, but this could likely be it.  I'll try changing up the routers.  I believe an AP by default turns of DHCP, and I imagine I still need to keep the static IPs I've assigned on these routers as well?  

[CrimpOn]

My practice is to reserve IPs in the primary router rather than set static IPs in devices. Either way works.