You can download the device's firmware from Epson website on the computer, and then connect the device and the computer by USB cable to update the firmware. If you cannot update over the network, try this method.
Access Epson website and download the firmware.
Connect the computer that contains the downloaded firmware to the printer by USB cable.
Double-click the downloaded .exe file.
Epson Firmware Updater starts.
Follow the on-screen instructions.