Why does a Wi-Fi repeater have to be directly at the socket?

Hello dear community of good questions, I got the Powerline adapter from Devolo today. In the description it says that the receiver must be directly at the socket and not at a multiple plug. I also tried it with a multiple plug, but it really doesn't work. I only have a few sockets in my room with multiple plugs because I can't use my monitors etc. With a socket. I can only mount the receiver on the corridor, but I want to connect it to my PC, ps4 etc. In my room with a LAN cable. Is there any other way than a direct socket connection?

A Powerline adapter goes over the lines, i.e. The power lines themselves. To avoid malfunctions, they should never be used with an extension cable and should always be directly at the socket.

You surely have a socket in your room, unplug the multiple plug and plug in the Powerline adapter, there are also some that have an integrated socket, most of them can do a maximum of 16A, that much, your "system" should not pull

You can also plug it into a multiple socket, but it may be that other inserted devices can interfere.

Thank you for your answer, but my socket is behind my closet and my desk on the opposite side. I want to connect this to LAN but I don't want a 10 meter cable from a socket to go across the room.

A direct connection to a wall socket is almost inevitable for Powerline.

Powerline works in such a way that the data is modulated onto the normal power line using a high-frequency carrier. However, other connected devices in the circuit also inadvertently couple high-frequency signals into the circuit. These can disrupt the Powerline.

In addition, with a multiple socket, these distributors usually have built-in interference filters. These filters can also filter out parts of your powerline signal.