Q: Apple Watch auto unlock on Sierra

Try toggling handoff on your phone and watch.

Automatically unlock your Mac with your Apple Watch - Apple Support

You can swap in a newer, compatible Wi-Fi card to enable unsupported use of the auto-unlock feature.

This is what works for me: Re: The message "Your Mac was unable to communicate with your Apple Watch" Keeps appearing when I try to set up my Watch to unlock my MacBook Pro

If you have an early 2013 13" MBPr, for example, you'd want the Wi-Fi card from a late 2013 MBPr.

Basically you want the Wi-Fi card from its nearest compatible relative.

Great... but if you have two mid-2015 MBPro's do I have to go backwards? (sarcasm)

Basically Apple screwed the pooch on this one. The two level authentication is their effort to be like Microsoft. Unfortunately Microsoft did a million times better and easier than Apple did. This feature just is not working despite everything I have tried. I even tried to pair the watch to the MBPro's and it does not even see the watch bluetooth wise.

You need this WiFi 802.11 AC card - BCM94360CSAX

Ok, I got it to work....for me. I activated the Apple Watch app feature "Unlock with iPhone" to ON. The unlock immediately started working. When I turn the feature off, it stops working.

Hope this helps somebody.

I tried the mentioned solutions.

My problem is that sierra recognize my iMac as a supported device for unlocking with apple watch but after a while it prompts me to enter my password. In 1 out of 10 cases unlocking works with my apple watch.

So there must be something that prevents sierra to identify my apple watch.

Any idea what's going wrong?