Linking 2 routers connected to the same modem

pigcanswim

Occasional Visitor
I have 2 routers(Asus-Merlin and Orbi) connected to an ONT that gives 2 different public facing IP. I would like devices from both network to be able to see and talk to each other. I suppose that means using static routes however there is no way for my routers to use the ONT as the middle man for both routers as it seems it can only act as a middle man for my routers to my ISP.

Internal networking
Asus is using 192.168.50.x
Orbi is using 192.168.1.x

After linking them up, I tried to look for the DHCP address so that I can attempt to do the static route but there is no such device listed. I check my Asus log and found that it's reporting this error repeatedly,
Mar 13 14:37:24 kernel: br1: received packet on eth0.v0 with own address as source address

Removing the cable connecting them both will stop this error.

using ifconfig shows
br1 Link encap:Ethernet HWaddr xx
inet addr:121.x.x.x Bcast:121.x.x.x Mask:255.255.255.0 (showing the exact same IP on my router WAN IP)
UP BROADCAST RUNNING ALLMULTI MULTICAST MTU:1500 Metric:1
RX packets: errors:0 dropped:0 overruns:0 frame:0
TX packets: errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0

Is there any way for the devices on the 2 routers to talk to each as I'm personally using Asus but my printer is located on the Orbi.
 

eibgrad

Part of the Furniture
If the two routers each maintain their own public IP via the ONT, then you can NOT simply patch an ethernet cable between them via their respective switches since that will make each part of the same logical ethernet segment. And then each router's DHCP server will become accessible from the other, which means you'll never be sure which network ends up configuring any given client.

What you need to do is the same thing you do anytime you need to access a different IP network; route between them, using either an actual physical router, or perhaps a virtual router in the form of VLANs. Given the equipment we're dealing w/ here, VLANs are likely NOT possible. But if you have a spare router available, even an old one otherwise just sitting on the shelf, that would probably suffice.

The other option (and perhaps the easiest) is just to route between them over the internet using port forwarding. In doing so, each router from the perspective of its own public IP is available to the other like any other device on the internet. Or perhaps configuring one as an OpenVPN client, the other as an OpenVPN server, and configuring a site-to-site VPN. The downside, of course, is that local access between the routers is forced over the internet, when we'd prefer it to remain local (i.e., behind their respective WANs). But depending on your hardware/firmware and skill level, routing over the internet may be your best/only option.
 
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pigcanswim

Occasional Visitor
using either an actual physical router
Suppose I am able to get a spare router, how do I go about setting the device to allow communication between both my original routers?

I'm guessing:
-Set spare as AP
-Get IP of spare from both original routers
-Setup static routes

But that will cause my spare to have multiple IPs and I think I may be missing out on something

Why are you using two public IPs?
Well, my internet plan offers up to 2G and using one router will only max out at 1. I rather not waste it and tried thinkering with it and somehow the ONT gave both the router their own IP and well, why not...

But the reason for splitting up is because I have my NAS on the network my device is using. And I prefer to have the network to myself as I will use it frequently.
 
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eibgrad

Part of the Furniture
Well, my internet plan offers up to 2G and using one router will only max out at 1. I rather not waste it and tried thinkering with it and somehow the ONT gave both the router their own IP and well, why not...

Gave both router's their own *public* IPs? It sounds now like you mean *private* IPs, when originally you said public. You need to be precise here in your description because it matters.
 

pigcanswim

Occasional Visitor
Gave both router's their own *public* IPs? It sounds now like you mean *private* IPs, when originally you said public. You need to be precise here in your description because it matters.
Yes, it's public facing ip. The one I see at whatsmyip.org

one of them is 121.x.x.x the other is 202.x.x.x
 

eibgrad

Part of the Furniture
Well if it is public IPs, then my original comments still stand.

No, you don't need an AP. You need a router. The LAN side is patched to and configured w/ an IP from one network and has its DHCP server disabled, while the WAN side is patched to and configured w/ an IP from the other network (DHCP or statically (preferred, so it doesn't change)).

Now you add a static route to the primary router on the LAN side of that router which points to its LAN ip as the gateway to the other network. Similarly, you add a static route to the primary router on the WAN side of that router which points to the WAN ip as the gateway to the other network.

Finally, you disable the firewall on WAN so that traffic is allowed to flow freely and unfettered from the WAN to the LAN. This can sometimes become a stumbling block w/ oem/stock firmware, and why third-party firmware *might* be required. Just depends on the router.

P.S. All this assumes as well that the ASUS and Orbi support static routes. Here again, that's not always the case. It varies from router to router, esp. w/ oem/stock firmware.
 
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sfx2000

Part of the Furniture
Assuming your service will assign more than one public IP...

Modem <-> Switch <-> Routers

Doesn't need to be a managed switch - any unmanaged switch will work here - remember, switches work at layer 2, so each router should get it's own DHCP assigned address.
 

eibgrad

Part of the Furniture
Assuming your service will assign more than one public IP...

Modem <-> Switch <-> Routers

Doesn't need to be a managed switch - any unmanaged switch will work here - remember, switches work at layer 2, so each router should get it's own DHCP assigned address.

The OP's concern is for communications between the local networks behind their respective WANs. Adding a switch between the modem and the routers doesn't address that issue.
 

sfx2000

Part of the Furniture
The OP's concern is for communications between the local networks behind their respective WANs.

Not my problem to be honest...

One can always to something more complicated to meet an end - but there, shared resources should be on one managed network, not two...
 

pigcanswim

Occasional Visitor
Not my problem to be honest...

One can always to something more complicated to meet an end - but there, shared resources should be on one managed network, not two...
Well, yes what you said is true. The problem lies in the fact that I'm the only power user in my family and I believe in getting more use out of equipments available than using one that is locked out or with restricted features and that's why the Asus is running Merlin and the Orbi is not running any custom firmware like Voxel.

My NAS which serves as a remote data server and some selfhosting application is public facing and connected to the Asus router for portforward and everything. Using a single managed switch means I will have to stop everyone in my family from using the network if I need to do any changes to the switch and as I do not have a switch, all changes are being made to the router instead and having only one router to test my changes and stopping my family from using the net is definitely a red card. Also as the NAS is public facing it could be a direct threat to the family if it's breached and we're all within a managed network so seperating them may also serve as a barrier between the most riskiest network and the typical user network.

That's why I explored using multiple routers hoping that whatever I do with my stuff will NOT jeopardize the usage of internet for my family which in my case, ended well. Having 2 public IP also allows me to test things a single public IP can do but will experience some inconvenience like portforwarding, strict access to the NAS etc.

And since I'm the only user for my network, it will be unwise to connect the printer to my network cause I will then need to change the network configurations for the printer everytime my family members needs it.

Lastly, my ISP have special requirements and using routers that have preset configurations is much more preferred as setting up the configuration and testing it will cause downtime and I'm sure my family will be very unhappy about not being able to use the net.

P.S. All this assumes as well that the ASUS and Orbi support static routes. Here again, that's not always the case. It varies from router to router, esp. w/ oem/stock firmware.
I've checked, my AX88U and the Orbi both support static routes. I'm now trying to get a cheap 2nd hand router to set this up and see if it does work out.


Edit: Managed to link them both using an additional router and I can now connect to the printer!
 
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