The European Regulation on net neutrality obliges the Body of European Regulators for Electronic Communication (BEREC) to issue guidelines. These guidelines were published on 30 August 2016 and are currently updated according to the BEREC work programe 2019. A draft of the updated guidelines is open for consultation until November 28, 2019. Further background information can be found here.
Please note that only the English language version is authentic. The German translation is non-binding.
The guidelines are available for download.