OpenVPN Support Forum

Hi,
I have an ISP router followed by a Netgear router, lets call these A and B where B is connected via LAN port to its WAN port. The subnet for A is 192.168.0.1 and B 192.168.1.1. On Netgear I am running dd-wrt firmware to setup OpenVPN server for which I followed this video:
https://www.youtube.com/watch?v=dwrR18_xO_Q

I have Server: CONNECTED SUCCESS
Local Address: 10.8.0.1
Remote Address: 10.8.0.1

Also setup the OpenVPN GUI software client with a DDNS address, which connects fine on Windows 10 to 10.8.0.2.

Now the problem is, although I have port forwarded in router A to IP address of Router B, which is 192.168.0.99 port 1194, I cannot seem to be able to see the local network. Instead when I use my DDNS on an external network (using my 4G mobile as hotspot) I get access to my NAS page on Router A, but on a different IP address and different port forwarding and for some reason.

I have some networking knowledge, but no expert, however, this is really strange and confusing.
Happy to send any logs if that helps, but appreciate any suggestions on what to do.

Many thanks

Bobby121418 wrote: ↑

Mon May 09, 2022 8:46 pm

I have an ISP router followed by a Netgear router, lets call these A and B where B is connected via LAN port to its WAN port.

Can you get rid of the ISP router? That's making things silly. A simpler configuration with just ONE router would be best.

Alternatively you could lose the Netgear, if the ISP CPE gives you the ability to set routes. But you'll probably have to run your openvpn server on a machine behind that router.

Bobby121418 wrote: ↑

Mon May 09, 2022 8:46 pm

The subnet for A is 192.168.0.1 and B 192.168.1.1.

Those are individual IP addresses, not subnets. The subnets are probably 192.168.0.0/24 and 192.168.1.0/24. And those are the absolute worst choices for VPNs, because those are default subnets for almost every off-the-shelf router. In most cases you are not limited to the router's default network choice. See RFC 1918 and get creative.

Bobby121418 wrote: ↑

Mon May 09, 2022 8:46 pm

On Netgear I am running dd-wrt firmware to setup OpenVPN server for which I followed this video:

1. I do not recommend dd-wrt because of some poor choices they made. See if OpenWRT is available for your device.
2. I can't review your video, but we do have a very good HOWTO I can recommend.

Bobby121418 wrote: ↑

Mon May 09, 2022 8:46 pm

I have Server: CONNECTED SUCCESS
Local Address: 10.8.0.1
Remote Address: 10.8.0.1

What? Local and remote address can't be the same.

Bobby121418 wrote: ↑

Mon May 09, 2022 8:46 pm

Also setup the OpenVPN GUI software client with a DDNS address, which connects fine on Windows 10 to 10.8.0.2.

Okay, that sounds better.

Bobby121418 wrote: ↑

Mon May 09, 2022 8:46 pm

Now the problem is, although I have port forwarded in router A to IP address of Router B, which is 192.168.0.99 port 1194, I cannot seem to be able to see the local network.

You did not say what "the local network" is. Are nodes getting connectivity through dd-wrt or the ISP CPE? The external tunnel IP:port/proto has no relevance for routing inside the tunnel.

Routing has to work both ways. The router has to know how to reach the VPN netblock, and the VPN has to know how to reach the LAN.

Bobby121418 wrote: ↑

Mon May 09, 2022 8:46 pm

Instead when I use my DDNS on an external network (using my 4G mobile as hotspot) I get access to my NAS page on Router A, but on a different IP address and different port forwarding and for some reason.

I am not sure what you're saying. I guess the dd-wrt is doing NAT to reach outside its network (through the WAN port.) That's normal and expected.

regards, rob0