PC and Printer on different routers connected through a modem in bridge mode

[pigcanswim]

This is a picture of my current networking

The configuration now:
Asus LAN 192.168.50.x WAN 1xx.x.x.x
-PC 192.168.50.50 (Static, Wired)

Orbi LAN 10.0.0.x WAN 2xx.x.xx
-Printer 10.0.0.4 (Dynamic, Wireless)

I would like to access my printer which is connected tru WiFi to the Orbi but I am connect to the printer through the Asus router because my modem is no longer a gateway. It's working as bridges for both my Asus and Orbi so there's no way I can talk to my modem or to the Orbi. I could connect to my Orbi WiFi however that would be an extra step and I will have to disconnect/reconnect everytime.

Is there any 'permanent' way for my PC to 'talk' to the printer?

Pardon me as my networking skills is not advanced.
I am thinking of connecting the extra LANs on my Asus and Orbi so they can communicate but I take it there will be alot of problems as they are on different subnet IP and I think there will be logical errors on the routers as there will be 2 routers giving my PC 2 network IP and will clash with its logic. (Please correct me if I am wrong)

 

[eibgrad]

I'm first trying to understand why each router's WAN isn't established on the primary router's network (192.168.1.x). That would be typical.

If that was the case, you'd have essentially the same problem as the following person.

How can I link 2 nets behind 1 modem/router?

Hope someone can help. I’m trying to set up two LANs behind my Telstra Cable Modem (&router) but allow them to access devices on each others’ net. Picture of the current configuration is below. I should note that net 192.168.2.x is via a 5-port switch. I’m trying to avoid running additional...

www.snbforums.com

 

[pigcanswim]

Sorry I think I may have left out a very important information, It not a actual modem but rather a optical terminal.

The terminal is an ONR that handles Optical network informations with router capabilities without WiFi.
My IPTV is connected to the router function of my ONR so that I can watch shows.

Both my Asus/Orbi WANs are public IPs.. In a way I am unable to send any private IP requests to my Modem because any private IP requests is either done by the router itself or sent to my ISP and gets ignored.
I believe that's the case I'm experiencing.

The case you shown is a double NAT on a modem but my network is 2 single NAT with valid public IP facing the internet.

I can use my router to ping 192.168.50.x but I cannot ping 192.168.1.x because it doesn't exist in my Asus router. The same goes for my Orbi for its 10.0.0.x network. I hope you understand what I am trying to say.

Long story short, my modem is not giving me private IP. Instead, I'm getting public IP by bridging with my modem so now I have 2 public IP using a single modem and 2 routers. My modem is a gateway to my IPTV but not a gateway for my routers. Any attempt to ping to my modem wont work as it is working in bridge mode, probably br0 for my Asus and br1 for my Orbi.

 

[ColinTaylor]

Directly connecting the two router's LAN ports would be a bad idea as you suspected. You would need another router in between them which seems overkill for one printer.

The other option is to route via the internet. So on your Orbi you would create a port forwarding rule something like this:

Source IP = 1xx.x.x.x <- The Asus' public address
External Port = 9100
Internal Port = 9100
Internal IP Address = 10.0.0.4 <- make this a static address
Protocol = TCP

* this assumes your printer uses port 9100

You should now be able to access the printer from the Asus network using the Orbi's WAN address (2xx.x.xx) and port 9100. No one else should be able to access it from the internet because you have restricted the source address.

 

[eibgrad]

^^ I agree that using the internet in this case is a viable option. In general though, I prefer to keep things local, and it would be possible either using another router (as ColinTaylor suggest), or given the right firmware, creating a VLAN on the ASUS (w/ a single dedicated port) in the same network as the Orbi, patching them via ethernet cable, and routing between them (iow, you could avoid another physical router). It's not an uncommon configuration for ppl needing *local* access between routers. But I have no idea what model of ASUS router it is, the firmware you're using, etc. Nor do I know anything about the Orbi's capabilities. That would make a big difference in determining what was or wasn't possible. So in the absence of such information, the easiest solution would be via the internet.

 

[pigcanswim]

I think I have a problem trying to set portforwarding with a fixed IP because it's a dynamic WAN I'm having. Also, my Orbi doesn't seems to have the option to allow source IP like Asus can.

My Asus is AX88U using Merlin 384.18 and the Orbi is RBK50 router/mesh system.

Well, before anyone question me why am I bridging 2 routers, I have a 2Gb plan and modem port only allow up to 1gbps speed. That's why I created another network to fully ultilise the 2Gb plan and to expand the wireless coverage that my Asus could not reach. I also do not want to double NAT my network so... lol.

 

[eibgrad]

All things considered, if port forwarding is off the table, I would suggest using an old router. Yes, it's overkill for just printer access. But when you're dealing w/ the issues of OEM firmware, and what I presume will be a lack of VLAN capabilities in Merlin (I'm less familiar w/ what is or isn't possible w/ his firmware; w/ FreshTomato VLANs would be trivial), the use of a physical router just seems easier than the alternatives.

You just disable the DHCP server on the new router, give it a LAN ip in the same network as the ASUS, patch its LAN to the ASUS, and patch its WAN to the Orbi. Finally, define a static route on the ASUS router that points to the LAN ip of the new router as the gateway to the Orbi's network. Relatively simple to implement.

At least that's how *I* would do it given the current circumstances (I always seem to have plenty of old routers on the shelf from years past just collecting dust anyway; doesn't have to be fancy either). And who knows, once you have general purpose access to the Orbi network, you may find it useful for accessing other resources, or perhaps implementing bi-directional access.

 

[pigcanswim]

Well, my plan was originally to be able to connect to my printer but if I use another router to 'bridge' my Asus to my Orbi, that means I could potentially also do configurations directly on my Orbi by using a PC and VPN into my Asus and attempt to connect to the 10.0.0.1 Orbi using LAN?

Right now I have web access from WAN enabled on the Orbi which I feel is rather insecure due to any potential 0-day port attacks.

I've experienced problems trying to connect to my Orbi using OpenVPN successfully and if this this way of connecting have a chance of working I may dig through my house for any old routers that I have not thrown out and test it.

 

[eibgrad]

To be precise, you are NOT bridging, you are *routing* to the other network.

As you suggest, if you keep the connection internal, you avoid the potential risk of exposing the printer to the internet. Esp. if you can't limit the source of that access to your own public IP. It just made sense if you wanted a simple, quick-n-dirty solution, *provided* it can be secured!

And besides, who wants to be denied access to a printer just because the internet happens to go done. Granted, not a common occurrence, but still.

As I said, this is NOT a complex problem if you have a spare physical router. Even one w/ OEM firmware should be fine. Just as long as you can disable its DHCP server, change its LAN ip, gateway, etc.

 

[pigcanswim]

Yea, I will look around my house to see if I have any spares. Otherwise I think I will have to continue exploring other alternatives.

Thanks for the support! @eibgrad @ColinTaylor