I have not set up an Epson but have a Brother wireless. I had trouble
getting it to work wireless with Ubuntu. So I booted in Windows and went
through the Windows install process. This assigned the printer to a port
on the wireless router. After that in Ubuntu
, printer was found
clicked through to appropriate driver and all is working.

I'm sure there is a way with Ubuntu to assign the wireless network port,
but I gave up. That was the issue I was having and seems to be the same
for you. Printer worked with USB but was not found by wireless until I
did the Windows set up. In fact then the first after that when I tried
to do the Ubuntu install, I started with the USB corded connected per
some instructions I found, but that messed up the wireless and my Window
setup nor Ubuntu would printer wireless.