Which model is it that you have?
Tech specs for Nest Wifi Pro, Nest Wifi and Google Wifi - Google Nest Help
I'm assuming you're following the placement guidelines as much as possible? See the "Improve coverage for an existing network" section below:
Where to place your Wifi devices - Google Nest Help
If you're still struggling after following those steps. Are you relying on the Wi-Fi mesh or have you hardwired them? Hardwiring them can often help improve performance in very large homes, and homes that have thick walls or lots of obstructions.
Hardwire Nest Wifi Pro, Nest Wifi or Google Wifi with Ethernet - Google Nest Help
It's worth bearing in mind Google recommends a maximum of 5 Wi-Fi devices in a single network. Adding more can actually be detrimental to Wi-Fi performance.
