## Short answer
Ad blockers do not work in Nougat until the developers make an update. A [beta version of AdAway][1] does the trick but requires to check the new "Systemless mode" in Preferences screen.

Other ad blockers will probably implement similar solutions

## Long answer
This is marked Community Wiki for others to contribute. The explanation is not fully clear to me too!! Everything is well explained in [#770][2]

Root applications do not normally have access to `/system` partition, even as root. This because the system partition is readonly by design. However, with `mount` command you can easily remount a file system in read-write mode and do whatever you like. This is what ad blockers and most root apps used in the past.

But Google [changed][3] the way the command `mount` work, to keep it in simple words. In Android 6, there actually were two coexistent implementations of the mount command, so if you didn't support `toybox` you could fall back to `toolbox`.

That is the **simple** reason why Nougat requires **all** root apps to update themselves if they ever need (and why ever in the world do you need to be root if not?) to modify the system partition


  [1]: http://forum.xda-developers.com/showthread.php?t=2190753
  [2]: https://github.com/AdAway/AdAway/issues/770
  [3]: http://www.xda-developers.com/android-n-testers-heres-why-your-root-apps-keep-failing/