Judgment of the Court (Eighth Chamber) of 2 September 2021.#Vodafone GmbH v Bundesrepublik Deutschland.#Request for a preliminary ruling from the Verwaltungsgericht Köln.#Reference for a preliminary ruling – Electronic communications – Regulation (EU) 2015/2120 – Article 3 – Open internet access – Article 3(1) – End users’ rights – Article 3(2) – Prohibition of agreements and commercial practices limiting the exercise of end users’ rights – Article 3(3) – Obligation of equal and non-discriminatory treatment of traffic – Possibility of implementing reasonable traffic management measures – Additional ‘zero tariff’ option – ‘Zero tariff’ excluded in the case of roaming.#Case C-854/19.