Route to other router subnet - 2nd gateway? or double NAT?

[astranova]

I've been setting up my OPNsense router gradually, while it's been behind my main router.
Original configuration was:

Modem --- OpenWRT router with 192.168.0.1/20 network --- OPNSense router with 10.10.0.1/16 subnet and others on VLANs.

The OpenWRT router has an external HDD shared on the network that I was still able to access from the OPNSense subnets. Today, I finally moved everything behind the OPNSense router and swapped the modem over to connect directly to WAN on the OPNSense router, but I'm trying to figure out how I can temporarily still access the share on the OpenWRT router until I get a chance to migrate that HDD to the OpenMediaVault server on the new subnet?

I currently have a LAN port on the WRT router still plugged in - it's tagged for a VLAN from the WRT router - and I've created an interface on the OPN router for that VLAN. I was trying to setup a 2nd gateway - and the OPNSense router gets an IP on the 192 network but I can't get it to access it from a subnet - I can ping it and ssh to it when I'm ssh'd into the OPNSense router though, and there is a route for it.

Or do I need to connect the WAN on the WRT instead - basically completely reversing the original config - but would I run into an issue where I can't access any of the 192 subnet from the 10 subnet due to the NAT?

[bartjsmit]

Why don't you configure OpenWRT directly on the LAN and bypass OPNsense?