@Kevin_Z It's connected via Ethernet. I don't have any settings to deactivate Private MAC. (Windows 10) I didn't use the QoS, only the speed limit. It's as if the deco x50 is too slow and doesn't...

@David-TP The speed limit doesn't work as intented : if I open youtube and start a video, it will bypass the speed limit and go above. It will also let the device go randomly above.