Try rebootiing the mesh. To do so in the App: Click on the "Internet" symbol => Select the "Main Deco" device => click on the "3 dots" in the upper right, then, finally, select "Reboot".

Your second drawing is exactly how I run my Deco's in AP mode ... with the caveat to remember that the 'modem' is actually often a modem (Internet gateway), a firewall, and a DHCP router. If you have...

I have not had an issue with multiple Deco's in AP (Access Point) mode. I will relay this 'story', though, about how I ended up having to "work-through" adding a new Deco to the existing AP network....

@Chriskoh Since it doesn't appear that you are using this as a router device, you should change the "Operating Mode" to AP (Access Point). On the default screen (Overview), tap the "More" at lower...

re: channels 12-13 not in US Excellent reason to at least have 'exclusion' band control. Perhaps, in addition, would be to have 'preferences' of channel selection. Others have mentioned devices which...

@tmhlc I don't know for sure, but I have a strong inkling the Master role in AP mode is primarily 'mesh management' ... and it may also be the "keeper of statistics" which are reported by the app;...