Router B is bridging Device B to Router A’s network, so they aren’t on separate vlans; thus, it shouldn’t require an mDNS reflector as that repeats mDNS between separate subnets.
Afaik, an mDNS reflector is only needed to cross subnets – both subnets and mDNS function on layer 3. Bridging occurs on layer 2, and since mDNS functions in layer 3 (ipv4 multicast is layer 3), the bridge itself is invisible to it.
This works if B has an interface that is connected to the A subnet
I’m not sure I understand exactly what you mean. Is it not given that if two routers are connected to each other then an interface from either of them will be connected to the other?
but not if you have a PtP between the two routers
What do you mean by PtP? Are you referring to something like WDS, or, in my case, relayd?
No, not at all 🙂. I’m referring to a configuration in which the two routers are linked through another subnet (using a separate link between the two) and this link is the point to point link. You usually assign a /30 so you can have an address for each router. This way the traceroute shows three hops instead of just two. However, since you’ve already told us that this is not your setup, what I’m saying shouldn’t matter to you. If you’re curious though, let’s keep talking :)
However, how comfortable are you with routing in general?
Ha, depends what you mean by that. If you mean manually specifying routes in a router, I think I generally understand it, but I am not at all confident in my abilities.
Yes, thank you! Usually, however, most of my issues seem to stem from knowing where configs are, what tools to use for what, or where to find things in the router user interface, etc.