Routing OpenVPN traffic across an 8-port network module setup - Best Practices?

licadiw273

Hi all, long-time user of OpenVPN here, but I’ve finally hit a wall that my basic networking knowledge can’t quite scale. I’ve recently moved my gateway setup to a more robust piece of hardware that utilizes a dedicated 8-port network module. The goal was to give me plenty of headroom for physical isolation between my home lab, IoT devices, and general family traffic, but the routing logic is starting to get away from me.
One specific point I’m struggling with is how OpenVPN handles the virtual adapter when I’m trying to bridge or route it across multiple physical ports on this specific module. I want my remote users to land on a subnet that only has access to ports 3 and 4 of that 8-port module (where my local servers are physically patched), but I’m seeing some weird packet loss and "destination unreachable" errors when I try to push the routes via the server config.
I used to just run a simple "road warrior" setup on a single-port mini PC, but now that I’m using these professional-grade network devices , the push-route logic seems to conflict with the physical bridge I’ve set up in the OS. I’m starting to wonder if I should be running individual tun instances for specific segments or if there's a more elegant way to handle this port density without making the server config file a mile long.
Has anyone else here dealt with high-port-count network modules while managing OpenVPN? I’m curious if it’s generally better to keep the VPN on its own isolated virtual bridge or if I should be tagging the traffic directly at the hardware level before it even hits the OpenVPN daemon?

The Johan

Bridging in OpenVPN is something you don't really do unless you really need it for some legacy applications that talk some protocol that just won't route properly. Routing really is the way to go. Bridging is not a great solution here.

If the system supports it you can use network namespaces. This creates a kind of isolated network stack with its own interfaces and routing. This is what docker does for example.

Another option if the system supports it is Policy Based Routing. You can have different routing tables instead of just the main one, and then define a policy like "if packets come from interface x, send it into routing table y". That way you can have identical routes in place but move traffic between different interfaces, without them crossing over and conflicting.

Another option is to use VLAN tagging.

Another option is to just rely on plain old routing and just make sure each subnet is unique and you don't use that subnet in multiple places at the same time.

ps; I removed the link you had in your post to an external site's network products page, because this could be seen as spam/advertising.