I wonder if others could give me some feedback on whether an issue I've recently encountered affects other devices and/or firmware versions or is unique to this unit?
VMG8924-B10A with (currently) V1.00(AAKL.19)C0 in regular routed mode.
I have several devices directly connected to its wired LAN ports. A couple of days ago I found that these devices cannot connect to each other because they cannot discover each other through IPv4 ARP or IPv6 neighbour discovery! The ports are part of the LAN bridge (br0).
What is strange is this only affects wired-to-wired device discovery; discovery and connection from WiFi devices (also on br0 via wl0) works fine (and visa-versa).
Despite extensive diagnosis I've not identified a cause or solution. I'm currently suspecting the Broadcom hardware switch block itself.
More detail:
Using tcpdump on the various devices, and the router itself, I can see ARP who-has (and IPv6 neigh-discover) packets going out on the target device's wired port (e.g. eth0.0), and on the target device I see them received and the ARP/neigh-advert responses sent back. Those replies do not show up on the router (on the source (eth0.0) or target (eth1.0) ports, nor br0) and the target device does not see them either.
As I said, this was working a few days ago.
I discovered this because the target device is running the squid-deb-proxy Debian/Ubuntu package caching server which it advertises via multicast-DNS.
The wired clients can receive the multicast-DNS packets, including from each other, but the connection attempt to the deb-squid-proxy was faiing due to neighbour discovery failing.