I have seen a similar problem with my M9 .... but it may not be the same.

The M9 is in AP mode.
With M9 connected via wifi and obihai plugged into main router (-not- M9), all is ok.
With M9 plugged into main router and obihai plugged into M9, the obihai is not assigned an IP address and does not work.

Maybe they messed something up with DNS forwarding on the latest build? Check if it is getting an IP (I think there is a handset key sequence to do that).

@US_Beta Reset the Obi device and the Deco still can't see the device. Tried rebooting my M9 too

US_Beta wrote

Could you try resetting your obihai 200 and if you can see the device IP at deco app then check the obihai need any port forwarding setting.

. My Obi is directly connected to my M9.