I have an SS Brewtech Unitank.
I initially bought an Ispindel, but the wifi signal would not get through the stainless steel fermenter.
I sold the iSpindel, and bought a Tilt. The tilt's bluetooth signal works through the fermenter,
Bluetooth also uses significantly less power than wifi, I guess thats the main reason they chose it.
I have an old android phone that is connected to my wifi home network, and the phone collects thr tilt bluetooth signal and sends the stats via google. If you dont have an old android phone, get a raspberry pi, but its more mucking about.