Hello Beanst and welcome to Apple Discussions.
Based on the error message it would indicate that you are connecting to the printer using IP, either via the Ethernet or wireless. Since there are three protocols to choose from, you have probably selected one the printer does not support - or it is not currently enabled on the printer.
I suggest you delete the current printer queue and add it again, this time selecting IP > HP Jetdirect-Socket. This is known as Standard TCP/IP Port 9100 on Windows, and is often enabled by default for most network capable printers.
If Jetdirect doesn't work then you should print a config page from the printer. This will show what ports are currently enabled. You may also need to check with Epson to determine if there is a different driver for the network enabled version of this printer, in case the driver you are using is for USB connections only.
PaHu