Ok. So I kinda went ahead myself a little bit and bought the cheapest router (TP-Link TL-WR740N). Now I'm suffering from the weak WiFi signal. I have moved my router to the attic, which temporarily solved my problem, but still I'd like to boost the signal even more. It would be helpful to know if anyone had experience with antenna mods on the router or client side (I am using ASUS R500VM laptop) and can share his knowledge.