FTTP and Google Nest

[#1]

I have recently upgraded to FTTP Full Fibre 500.

My house is built on a hill so I have a downstairs living area towards the rear of the property - so a level down from where the ONT box is, and then also an upstairs. The signal from the ISP provided routers never reaches the downstairs area so I have a Google Nest mesh network.

The Nest router point is connected directly to the ONT, then I have a switch with a CAT6 network cable running downstairs to connect to the Nest point down there (and a few other things running off the switch - hubs for smart heating, lights etc). There is also another Nest point upstairs in the bedroom connected via WiFi.

This set-up worked great with the old-fashioned broadband, but with FTTP 500 I will regularly get 350 mbps off the downstairs point - fine - but then that drops almost dialy to about 30 mbps.It's a similar story upstairs - standing 1m from the hub I will get 40-50 mbps. A restart of the network returns the full speed but it will drop again within 24 hours.

Is this a problem with Google, or am I being throttled?

Thanks for any help.

[#2]

Is this a problem with Google, or am I being throttled?

@davidjones533  Plusnet dont do any throttling, There a possibility of contention in the Openreach network but my guess would be your problem is the Nest.

Firstly you need to do any speedtests using a Wired connection, there are too many variables that can affect wireless speeds.

[#3]

30 mbps is often ( there are a number of variables here) the max speed of 2.4 GHz WiFi.
Which band is the WiFi device connecting to when it slows down?
Does putting a device in airplane mode and back on again speed things up?