Hey @SBtt
When you run a speed test through the Google Home app through Wifi > Test Network, the results are the speeds between the router and ISP. When you run a speed test from a device, the results are the speeds the device itself is getting to the internet site and will vary; this is due to the device settings and/or limitations and not the network itself on most occasions. On occasion it can be due to a setting on the router that is incompatible with the device but that is usually quickly identified.
I read through your other posts and see that you have likely performed the below but there are now troubleshooters to check your internal network and internet connections that were not available in the past and may be worth looking at. They are very similar but it still may be worth running both to verify:
How to improve Nest Wifi Pro, Nest Wifi, or Google Wifi speed and performance
Troubleshoot slow internet on Google Nest Wifi or Google Wifi
Just FYI: you can run a device speed test similar to what you are running from an online site by going to Google Home app > Wifi > Devices > select device > Check device speed (at the bottom). You can alternatively select "Check all speeds" and it will do the same for all connected devices but it will take time if there are a lot of them.
Let me know if you have any further questions.
