I have a 3 node Deco X20 WiFi mesh system. Access point mode still is not acting as simple media bridge to existing wired network behind another firewall-router. I would like a proper access point where one subnet applies to both wired and WiFi and the Deco X20 lets my main firewall-router provide the DHCP.

The Deco X20 in access point mode still seems to insists on being a self-defined gateway routing to a WAN upstream. This of course means only Internet traffic works and all local subnet traffic is killed regardless of using Guest network SSID or main SSID.

Latest firmware and mobile app upgrades were however great improvements. I can at least turn off DHCP service in access point mode to prevent clashing with the main router and eventually crashing its DHCP service. Previous the Deco X20 DHCP would, oddly enough, eventually broadcast out what was otherwise treated as a WAN interface after an hour or so. Having 2 competing DHCP services on the wired network was not good.

Yes as suggested elsewhere the Deco X20 does work behind another router if you set it to explicitly gateway mode in a "double NAT" configuration where the Deco WiFi mesh has its own subnet. Messy. Potentially unstable. etc.

Oh yeah I am only using IPv4 overall. Is it possible that only IPv6 mode works and was tested?