Hi, If your b box is in router mode and your Deco is also in router mode then you may have different subnets whihc may be your issue. Also, it's usually recommended that you turn off the wireless on...

Hi, maybe the M9 doesn't have the feature yet. Not sure. App version I am using is 1.7.7. This is what my wireless settings screen looks like...

Hi, it's under Wi-Fi settings, not the Advanced settings

a 'crude' check is to ping each deco. i find the pucks on ethernet return <1ms, wifi returns 3-5 ms...

maybe you can try and nail down the issue by setting up the guest network and turn off 5ghz for that network. see if that connects.

I have my NAS setup like this and it's fine...I actually have the 2 deco pucks on second switch attached to the first. NAS is on the first switch like your diagram.