@Network_Nation 

Hi, 

Yes, the model is HB810.

Would there be any error message when Google nest hubs can't be grouped together?
The message on the screen is "No devices found on this network."

In Google Home under the devices tab, all the devices are listed there. Voice commands has no problem.

Under the settings tab, this is the place where the group creation is done. When I click on Devices, groups and home it indicates that there is no device found on this network.

As for the screen mirroring, I used airplay. The TV for screen mirroring is not listed on my iPhone. 

  @Network_Nation 

I have the same problem. Singtel engineer came yesterday and setup the router and everything works except all my Google devices can't be connected. I reset all my Google devices, Mini, Nest, Cast.. and the setup using Google home was successful. When I go into the device on the app, it says no network found. I tweaked the Aginet the Wi-Fi management app from TP-Link, even removing the Wi-Fi password. I even took the Google devices and placed it next to the router... None of those steps help. Any idea what might be the issue?