RF module 1cm range

I’m playing with the Arduino for about a month, and I’ve stucked :frowning: I’ve got: 2 Arduinos, RF transmitter, RF reciever, button and LED. My project is very simple - when I’m pressing the button, LED connected to another Arduino is turning ON. For about a day I was able to control LED from another room and everything worked fine. Yesterday I backed to my project again, and the distance that I was able to reach had shrinked to 1 meter! Today it suprised me with 1-2 centimeters max range. I’m guessing that tomorrow it won’t work completely. The best thing is, that I’ve tried

  1. changing RF modules to new pair
  2. changing power supplies
  3. soldering an external 17cm antenna
  4. even changing the Arduinos.

Anybody can tell me what the hell is going on? It is the same code, same room, and exacly same desk as with the first test.

Thank you!

Do not double post.