that explains a lot! My C6 v2.0 does not support it, but v4.0 does, so I will have to replace my router. Thanks @terziyski

Documentation on How to set up QoS shows an image that include QoS with submenus for "Settings" and "Database". But in my case the QoS menu does not have any suboptions, see: and there is no QoS rule...