I just upgraded my wifi network with 3 Deco M9 plus in AP mode, connected to my old Asus AC88U. I kept the Asus as the main router mostly to keep the link aggregation to my main server and the fact that some of my stuff are concentrated around the xDSL plug, so better to have them all connected via ethernet (hence the 8 ports switch comes handy).
When I was using the wifi from the Asus, I can chromecast from my phone (connected on Wifi) to my soundbar (connected via ethernet to the router).
Since I switched off the wifi of my router and replaced it with the Deco, this is not possible anymore. Any attempt to cast seems seen by the soundbar (that switches to casting mode) but it seems the handshake doesn't happen. The soundbar if not visible via Google Home app either.
I have IGMP proxy and snooping enabled on the router and the MDNS request are propagating from the wifi network to the wired network. So the issue doesn't seem to be my router. I tried moving the connection to the ethernet port of my main deco point, same result. For some reasons, my soundbar doesn't want to connect to the new wifi so I cannot try all on the same network.
Any idea is the deco M9 in AP mode would block incoming chromecast connection?