Question

Greetings.

I have two RUT955s with the latest firmware, and I need to establish a communication between the devices below the two routers. Ill attach an img with my small network setup.

To describe it with words as well:
Router 1 creates a 2nd lan WiFi network using its wlan0-1 interface, with an IP of 10.0.0.1, and gateway 10.0.0.2.
Router 2 joins this WiFi network using its wlan0 interface, with an IP if 10.0.0.2 and gateway 10.0.0.1.

So far, Router 1 and Router 2 can ping each other using their respective CLIs. Also, devices under Router 2 can ping 10.0.0.1 successfully. The issue is that a device under Router 1 cannot ping 10.0.0.2 for some reason.

Ive checked firewalls, static routes and still the same. I replicated this setup twice to figure out if its a problem of a single router, but it persists, and from this i assume that its working as intended.

Is there something ive overlooked that makes this happen? Would removing the "in-between" 10.0.0.0 network and just adding Router 2 into the 192.168.1.0 lan wifi of Router 1 change anything (Of course provided i change the IPs of the Router 2 network)?

Answer 1

Hello,

Thank you for the detailed description of the situation and the attached picture.

If you need a quick solution: Simply change one of the router's LAN network to a different one (e.g. to 192.168.10.0/24) and that should resolve your issue.

Meanwhile, if you want more detailed aspects, here are a few comments:

 - The reason why your "Pi 1 - 192.168.1.32" cannot ping the 10.0.0.2 IP address is most likely related to the fact, that both of your routers are using the same 192.168.1.0/24 network. Therefore, when Router 2 received an ICMP ping request from the 192.168.1.32 device, it sends the response to the Pi 2 device, which has the same exact IP address. However, since Pi 2 did not initiate this ICMP request, it drops the packet.

 - In this situation, an additional LAN interface on Router 2 does have help in any positive way. You can simply have an access point created directly on the default router's LAN network.

Comments

Wow you are a godsent. Changing the IP of the router 2 network to 192.168.2.X makes devices ping the other router nicely. It is still strange how devices under Router 2 could ping Router 1 just fine but not the other way around.

The main target of my project is to make any devices under router 1 be able to ping any device under router 2, and vice versa.

Now that i removed the 10.0.0.0 network and just connected Router 2 into the lan network of Router 1 this happens:
Devices under router 2 and router 2 itself can ping router 1 and any device under router 1, but Router 1 and its devices can only ping router 2. Trying to ping devices under router 2 results in failure.

This situation is an upgrade over the previous one ill be honest, but does this mean that i have to set up some static routes on Router 1 in order to make the communication two-way? Or am i missing something again?

---

Hello,

Thank you for your reply.

Indeed, in order for Router 1 to know about the local Router's 2 LAN network, a static route is needed on Router 1. Sorry for forgetting to mention this yesterday.

On your Router 1, navigate to the "Network -> Routing -> Static Routing" menu, and create a new static route rule (here "192.168.2.x" (IPv4-gateway) should be set to Router's 2 WiFi WAN IP address):

Once this rule will be created, Router 1 should be able to read Router 2 and its local devices.

Meanwhile, a static route is NOT needed for Router 2, since it is used as "WiFi WAN", meaning that all of its outgoing traffic is sent through this WiFi interface regardless.