Open Device Manager and look for:
Bluetooth
Network adapters → “Qualcomm FastConnect” or similar.
If not, then:
Download Surface Pro 11th Edition Drivers and Firmware
https://www.microsoft.com/en-us/download/details.aspx?id=106119
In Start Search type services.msc and ensure the following services are running and start-up type is Automatic:
Bluetooth Support Service
Bluetooth Handsfree Service
Bluetooth Audio Gateway Service