This is great, but imposes few problems, such as UPnP being only visible in their network. Another problem that would be great to be solved is how to cover more area using CeroWRT bound by Ethernet (as opposed to WDS).
Some houses are big or have thick brick walls that blocks wireless propagation. To solve this using different routers will help. Since gigabit ethernet is way faster and more reliable than extending the range using WDS, it is desired to use it to link different routers.
It is expected that if you have multiple routers with the same SSID, if they use a single DHCP IP pool, the devices can migrate transparently from router to router, without loosing connectivity. Usually this is done by linking the routers using their LAN, giving them the same WiFi SSID and disabling the DHCP in all but one router.
However given CeroWRT multi-network scheme, it will break transparent migration across routers with the same SSID. If one device connected to sw00 (say IP: 172.30.42.93) on main router, then walks towards the signal of the secondary router it will need to be reconnected because the flow from the main router to secondary doesn’t happen through sw00, but se00, that doesn’t know the .93 IP! The device would then reconnect with an IP within range 1-30 (se00).
I’ve been thinking about alternatives, none of them is great and would like your ideas. Likely integrate the result as a new feature of CeroWRT.