[all variants] intel wireless 3165 problem -- hardware or bad driver?

Hi, I am a complete newbie to Ubuntu and I have a problem with WiFi. This is on a completely new laptop with no Windows or other OS to compare.

This new laptop with Ubuntu has weak WiFi coection and is very sensitive -- even a chair between laptop and router causes the coection to be significantly lower even though the distance is about 1.5 meters. My old Toshiba L300 has no such problem. I also use another WiFi that is few meters from my room and there are some walls in the way but my old Toshiba sees is quite well and it's usable. This new laptop on the other hand coects to it but the coection is so low that even Google takes long to load.

Is this hardware problem or can it be that I just have bad driver?
How can I check what driver do I have?

I have Xubuntu 16.04 and the device is Intel Wireless 3165.

Sorry for my English, I hope it's still understandable.