Thanks for your replies.
For me it can’t be a problem of the range. We got an open living room.
Homey is on a sideboard - 2,5m away is the Phillips remote - and max. 5m away from homey (2,5m away from the remote) is the fibaro plug. No walls or other signal blocking things are between it.
Ok - the plug is behind the couch - but hey - its wood and textile. If this blocking the signal, the signal comming from homey would be worse.
And - the signal from homey to a Fibaro Sensor on the other side of the living room (10m) works also fine! No problems.
Maybe @Marcel_Ubels is right and the plug itself is damaged. But how can I verify it, that the seller will accept a guarantee replacement?
And what you mean with “try developers-page to check the mesh” - I don’t know anything about it.
Maybe theres a firmware update for the Fibaro Plug - but sadly there is (imho) no option to update it without a 400€ HomeCentre
P.S The remote control also controls a light strip behind my tv. Never got a command problem turning this on/off.