How to encrypt My Cloud 3TB?

Is it possible to encrypt my My Cloud 3TB (Firmware 2.21.126) so my files are safe in case the device gets stolen? I’m running macOS Sierra.

Officially? No, there is no hardware or firmware based encryption offered on the single bay/single drive My Cloud units. Unofficially? One can use any number of third party encryption programs to encrypt the files on the My Cloud. Further there may be Linux based services one may be able to install using SSH to provide some sort of encryption since the My Cloud firmware is Linux based.