Sky Q main box loses internet when mini box is added to network

[Sky+help+123]

My main sky q box is connected by Ethernet cable to a Google Wi-Fi point. The google Wi-Fi point is connected via an Ethernet cable to the router. The setup has always worked fine with no issues. I ordered a sky Q mini box this week and that is connected to the network via an Ethernet cable in to another google wifi point. However as soon as I connect the mini box to the network the main box starts dropping out from the internet. Which is annoying when you're trying to download or stream something but then also means the mini box can't connect to it either. When the main box is dropping the internet the connection via wifi to the Google point is fine so it definitely has access to the internet. Any ideas?

[PandJ2020]

The default will be using Sky's own Mesh network and not your WiFi points.

Try Disabling WiFi on both the main Q and mini's.

[Sky+help+123]

Thank you for your reply. Both sky boxes and the sky router all have Wi-Fi switched off.