Q: Can't connect to WiFi, problem with distance from router

Hi, my WiFi is working fine, but only if I am close enough to router. Close enough means maximum 1 meter from router, if not, I can't connect. I didn't have problem with WiFi on Yosemite, but now it's annoying, because my laptop is useless. No problem on my iPad Air 2 and iPhone 5S. And I have this problem everywhere, not only in my flat. Where I used to connect before upgrade to El Capitan, I am not able anymore.

Do you know what to do, or it's just another El Capitan issue and I have to wait for update? Thanks for response.