Router A & Router B (each different subnets) - how can I access LAN devices connected to B when i'm connected to A?

Question

I have two WiFi routers:

• Router A is my ISP Router and is connected to the Internet.
• I've now added in a second WiFi router (Router B).
• Router A and Router B are connected together by LAN cable (WAN port on Router B connected to LAN port on Router A)
• Router B is on a different subnet to Router A.
• Router B is running DD-WRT and operating in 'Gateway' mode with the Gateway IP address being Router A.
• Router B is configured with a working OpenVPN connection.
• Router A subnet uses Pi-hole as its DHCP server. Router B is its own DHCP server.

Everything works fine. If I connect my phone to Router A by WiFi, i get Internet which is NOT protected by VPN. If I connect my phone to Router B by WiFi, I get Internet which IS protected by VPN.

Now the problem: Plugged into the LAN port on Router B is an IP Camera. I want to be able to view the Camera using my phone connected to Router A by WiFi.

I thought I could do this using some kind of 'static route' or port forwarding or something configured on Router B which would allow local IP addresses from Router A into Router B, but I couldn't get anything to work (i'm not really sure what i'm doing).

Or, i thought I could use 'normal' Port Forwarding rules configured on Router B which would allow traffic on a given port from the internet via the public IP address provided by my NordVPN connection. So in effect I could go out of Router A onto the Internet and back in from the Internet to Router B. I couldn't get this to work - would the OpenVPN connection prevent this?

Slightly feeble diagram below:

  Internet      IPCamera (192.168.1.2)
    |             |
    |             | 
192.168.8.1     192.168.1.1 (OpenVPN)
(Router A)      (Router B)
|     |           |     |
|     -------------     |
|                       |
WiFi                    WiFi
|
Phone (192.168.8.2)

Any advice on how exactly I can browse my IPCamera (192.168.1.2) from my Phone (192.168.8.2) ??

Answer 1

This can be done with a reasonably standard hookup.

(1) Connect a LAN port on Router B to the Router A network.

(2) Give Router B a static IP address on Router A (so it does not get lost on restarting)

(3) Turn DHCP OFF on Router B.

Now devices on Router B will get main network IP addresses and all will work in harmony.

Answer 2

Replying to John:

thanks for replying. I think you're describing a standard Wireless Access Point as I've created before using old ISP routers to extend WiFi coverage. However, isn't the difference that my Router B is using OpenVPN (ie. NordVPN) and it uses different DNS servers and so they need to be 'farmed out' to connecting clients by using DHCP on Router B.

Or are you saying, that the DNS servers that NordVPN told me I had to use is nonsense and I can just use my normal Router A DNS servers (Cloudflare) and the OpenVPN tunnel will still encrypt traffic for any & all clients connected to Router B ?

(Not sure why I'm having to answer my own question in order to respond - there appears to be no 'add comment' link)