I found one answer on a different thread (can't find it now) that reportedly solved the problem by manually assigning the printer a static IP address using the printer's control panel. The problem with this solution is that you must ensure that this IP does not match an existing or future dynamically assigned IP in your local network.
A more robust solution for me, on my home network, was to assign an IP using the DHCP Reservations list in my home base station. Here you are telling the automatic IP assignment program running in the router to always assign this IP to the printer (using the printers MAC address to identify it). This was quite easy in my case since it was an Apple base station and I could use AirPort Utility.
The key point though is that many of the "printer won't wakeup" problems I've noticed in mulitple threads (and I've experienced for years) are likely due to the printer waking up and getting assigned a different IP address. And that assigning it a fixed IP is the solution.
