@highwire I think it's a function of how the wifi to Ethernet bridge mode works in Tomato & DD-WRT, and perhaps other f/ws. I've been running DD-WRT bridges on a Linksys e2000 & e3000 with a number of different APs for a few years (currently N66). If you search on those firmware's forums or guides on how to setup the bridge they mention lack of bridged device MAC pass through as seemingly an unavoidable caveat. My understanding is that MACs would flow through using WDS, but the encryption is limited to WEP and I believe it might be restricted to 802.11g, whatever it was there was a serious performance downside.
The DD-WRT style bridges are imperfect but at least allow WPA2 and 802.11n. It depends on what tool you use to scan your network, here's a side by side w/ Fing & iNet Scan for iOS. You can see on the left Fing has a +2 & a +3 by my bridges (192.168.1.2&3) to signify that there are multiple active IP addresses within those items (if I click them I can drill down and see them). Fing doesn't show those items individually in its listing of all my IP addresses active though. The MACs Fing does show on my bridges are the 5ghz wifi radio MACs on those bridges.
On the right, iNet scan does actually break out stuff behind the bridges and list it by IP (such as the AppleTV and one of the TiVos), but you'll also notice that MAC addresses aren't visible for those items.
I can ping items behind bridges all day by their IP & it works fine, also, many of my bridged items that happen to make extensive use of Bonjour/zero-config which seems to have no problem working it's magic without MACs. Theoretically the switches ports of the bridges know what physical MAC is being plugged into them and routes it accordingly, but truth be told it could also be multi-casting to all of those ports what it receives on wifi and I don't know if I'd be able to tell because the top speed that traffic gets sent to any one bridges device is less than 90 Mb/s or so (even in best case, based on how I use them in my setup).
From the router's perspective, it tends to see the bridge's MAC but has confusion over aligning that with an IP, and also the friendly name I have that IP in the static assignment. It might take a stab at it, but it usually will mix up the bridge MAC w/ the IP of something behind it, even if that IP isn't the one assigned to the bridge. It (the router) doesn't know any better.
FWIW I assign everything static IPs in my main router (for my own segregation and ID purposes), and also have STP on all APs & bridges, though not positive I actually need it. I have no set routes setup and nothing fancy on the DD-WRT end. One thing I'm curious of would be to get IPV6 functioning on my bridges since I've got it working everywhere else, curious if that would allow better transparency. But as configured, it has worked with rock like stability for quite some time, all devices see each other, and my bridged devices all have very strong, consistent connections.
I just work under the knowledge that completely "normal" behind bridge visibility with friendly device name, IP, and MAC isn't a possibility at this time, at least not based on what the DD-WRT community is saying. But for me, it works great and way better than any alternative. And I can do more helpful diagnosis of current network config & problems from mobile apps, more often than not, than from the router UI (for this and any router I've owned.
And I also have a small 5 port hardwired switch to another media area, and peculiar things happen in the client list on the router to those devices but I think it's because it has one TiVo on 24-7 and 3 other devices that actually will take an IP on the rare occasions (once or twice weekly) that they need it (bluray player, smart tv, etc). But they are in max Eco power saving mode which seems to twilight them pretty hard when not in active use, vs PCs that might still maintain a little traffic over the LAN when asleep.