dd-wrt router as station bridge not routing traffic

I have a dd-wrt router set up as a station bridge. It was working for a while, then suddenly stopped. I’ve done everything (reflash, hard resets, reconfigure, etc) and can’t figure out what’s going on.

The router connects to the gateway/AP (192.168.2.1) just fine, and the desktop (192.168.2.111) connects (via LAN) to the station bridge (192.168.2.112) just fine – a DHCP request goes out which succeeds, and the desktop pulls an IP from the gateway router/wireless AP (the MAC of the desktop has a reserved IP in the DHCP settings of the GW).

I can then ping the station bridge, but I can’t ping anything else on the network, nor can I access the outside world.

From another device on the network, I can ping the desktop and it responds.

The only issue I had following the guide (https://wiki.dd-wrt.com/wiki/index.php/Client_Bridged) was that there’s no “Filter Multicast” check box – I can check “multicast communication” under “Block WAN requests”, but that check box doesn’t stay checked.

Otherwise, I’m stumped as to where the traffic is vanishing and why?