Android Wear 2.0 removed synchronization of the Do Not Disturb state between the watch and the phone. This application restores the Android Wear 1.5 behaviour with minimal or no battery life impact.
The application does not run in the background except for a second or two when Do Not Disturb is toggled.
Follow the steps below to activate watch to phone syncing:
1. Install and launch the phone app.
2. Tap the "Grant Permission" button and grant the app the requested permission.
3. Install and launch the watch application from the Play Store.
Version 1.1 of the app optionally adds support for bi-directional sync for users able to use ADB. To enable phone to watch sync, users need to manually following the steps described at the link below.
Source code: https://github.com/blunden/DoNotDisturbSync