My wireless Epson printer appears offline, often. Why?
Solution 1:
I found I had to delete the printer from Devices and Printers. Then add it back in by using it's IP address. I don't claim this will work for everyone experiencing this problem, but it is worth trying in case you encounter this problem.
Solution 2:
Per my answer here, the problem is to do with the device driver binding the printer to a working network port. I have to repeatedly assign the printer to the WSD port and then back to the TCP port. Then it works...