If you are having trouble getting the new Universal Clipboard working (e.g. between MacOS Sierra and iOS 10) I finally got it to work – after two chats with Apple Support.

The key seems to be logging out of iCloud and logging in again after upgrading. There are various things which need to be updated. It really should be a standard part of the upgrade. You also need to do this to get two-step verification to work properly on all your devices.

While Bluetooth and wi-fi need to be enabled on both devices, (1) the devices need not be paired (in fact, I could not pair them) and (2) it’s ok if your Mac is also connected to the Internet via a direct ethernet connection. Having wi-fi also turned on doesn’t affect your ethernet Internet connection.

In fact, having wi-fi on also also helps the new MacOS Siri know your Mac’s location, so you can ask Siri about the weather and things like that.

I was able to do things like copy a photo from my iPhone and paste it into Notes on my Mac. Quite cool!

So again:

1. Sign out of iCloud and sign back in on both devices. You just need to do this once. And of course it must be the same iCloud account.
2. Make sure Bluetooth is turned on on both devices. Pairing is not needed.
3. Make sure wi-fi is enabled on both devices and signed into the same wi-fi network. This does not interfere with your Mac’s ethernet connection, if you have one.