Wireless connection solution?

[3dcrgr]

Forget the USB. Pick up the RS232 Tx and Rx lines and feed them to a Moxa serial to ethernet.

There are USB <> ethernet but I have no experience with them.

But my printer does not have a RS232 output only USB.. or there is another way?

suggest you pick up a raspberry pi2 and run octoprint.
you can feed your rpi2 with either eithernet or wifi
you can setup a usb cam and there are free android apps that let you control your printer and view the camera
working great for me
edit : just make sure to install the gpx plugin
if you use slic3r you can go right from slic3r to the printer/octoprint
if use use simplify3d, you can just turn off generate .x3g and save the gcode to your desktop and then drag and drop to your octoprint browser session.

Will it work with Makerbot slicer? Where I bought my FFCP did not provide me even an option to purchase Simplify3D and I tried only Makerbot.