Build Your Own SLA/SLS

Hi. I have problem with connecting my Chinese Ramps 1.4 and Raspberry pi. I have installed CW Host as written on Github, Ramps 1.4 works (I checked with test code if stepper spins). But when I try to connect from PC browser it shows me CW Host interface but I can't do anything. "Problem communicating with host printer. (http:500)" is all what I got from it.

So anyone knows what I am doing wrong? I am using reconfigured Marlin firmware and my goal for now is just to spin stepper. I will add other components later... Please see my current setup in attachment.