I think I set this right: Network->Routing->Add->(Interface: wwan, Route type: unicast, Target: 192.168.0.1/24, Gateway: 192.168.1.1)
That doesn’t seem right. If you’re using the exact same subnet numbers I’ve used for example: that’s be target 192.168.1.0/24 (B’s network) gateway 192.168.0.2 (B’s IP on A’s network as a WiFi client).
Router B is on two networks at the same time: its own (192.168.1.1/24) and A’s network (192.168.0.2/24).
Router A is only on its own network (192.168.0.1/24) and talks to router B as just a client on its network (192.168.0.2). Whenever it has data to send to the 192.168.1.x network, it sends it to 192.168.0.2 which is on that network and will relay it.
How would I go about doing this? I can’t find any definitive information on how to disable NAT in OpenWRT.
Router B would wan configured as a WiFi client with a static IP of 192.168.0.2/24 and default gateway of 192.168.0.1 (router A). The regular default route will do just fine, as that will cover A’s network as well. We’d only need to configure more if there was a third router involved. From there you just need to disable IP masquerading option in Network -> Firewall (you want it unchecked):
You don’t need masquerade even though it’s technically a “wan” because A knows how to send traffic to B’s clients, so B itself doesn’t have to pretend its clients come from itself.
I do need this. I believe this would then require an mDNS reflector, right (it wasn’t required before as relayd was bridging the networks)?
If that proves too complicated, I’d consider trying out the GRE tunnel method your original article suggests as an alternative to relayd. It’s kind of like a super basic VPN that I think can be hardware offloaded so I wouldn’t expect much of a performance hit, maybe even less than the relayd option.