Wi-fi printer goes Offline

I have an Epson SX420W wifi connected to a router Belkin 54g. The network consists of a desktop PC and a notebook with Windows 8.1 Pro 64bit, and a notebook with windows 7, all connected wirelessly to the router and all with the latest epson drivers installed. The printer connects to the router is successful, as well as the network test from the panel of the printer. Installing the printer on the various devices was successful, as well as various proofs. The problem is that sometimes the printer is detected by the devices on the network like "offline", even though it is turned on, properly connected, as the test outcome. What happens for no apparent reason, in some cases it works perfectly while in others it is offline.

Do you know what can depend on and how to fix?

Wi-fi printer goes Offline