Devstack does not run services :)
Devstack runs as screens, if you want to restart any OpenStack service, get into screen using screen -r.
For example to restart nova network:

  1. Go to nova network screen which is screen 9, using the command CTRL+A followed by 9. 
  2. Kill the nova network using CTRL+C 
  3. Restart it using "up" arrow and enter.

**Remember you cannot reboot your machine running devstack. For further details see this article.

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