@makk509 

What is the model number of the powerline adapter that you have? It should start with TL-PA or TL-WPA.

@Tony 

Hi, the model number is TL-WPA281(UK)

Ver:3.0

Thanks

@makk509 

Have you tried factory resetting the wireless adapter, leaving it in a defaulted state, then testing the connection of the devices?

@Tony 

Hi Tony, yes I've tried resetting it. The extender works fine in general, anydevice connected to it has access to the internet and functions fine. It's just this issue when the device is part of a Google Home network.

The smart speakers connected to the extenders work fine on their own I just can't control them with a phone that's connected to the router. I also can't include them in a group with devices connected to the router. It's as if the extender and router are on different networks. 

Think I might have found the issue. Even though I used WPS to connect the extender and so the SSID and authentication was identical on the router and extender, there appears to be an internal network name field within the Powerlin extenders network settings. It was showing as 'unknown' on my device. I changed this to default network name from these devices and everything appears to be working correctly now.

It's only been a few hours so I'll monitor the situation but it's looking hopeful.

Thanks