mirroring on diferent firmware version

Hello Mario_Franco,

Mirroring feature was changing many times since it was created, so the compatibility between major releases is not officially supported.

Important: Connection and persistence mirroring will not function properly if the BIG-IP systems in a high-availability pair run BIG-IP versions with different mirroring transport protocols. For example, standard upgrade procedure calls for upgrading one system in the high-availability pair while the peer system temporarily runs the older version. However, if you use an upgrade path where the systems in the high-availability pair are running BIG-IP versions with different mirroring transport protocols, mirroring will not function during this time.

https://support.f5.com/csp/article/K7225

Despite of this, mirroring protocol should be quite similar since v13, so maybe you have some chance. Anyway, to confirm the compatibility, you need to test it on your own lab.