Printer Wireless, Networking & Internet

Like the title says, my wirelessly connected HP printer keeps going offline. I eventually always manage to get it to work but I can never figure out how I did it and it just seems to come back "to life" all by itself. Every time this happens I try turning it off and on again, usually this doesn't do anything, re-install the driver, etc. Eventually one of these actions seems to tickle the printer and it suddenly makes itself available. 

I've configured a static lease on my DHCP server so the printer definitely gets the same IP address every time. When it is working correctly I can access the printer's web control panel. After a period of inactivity (which I'm not sure if it's minutes or hours since I use my printer very sparingly) the printer will go offline. If I try to access the web interface my browser just says "Connecting..." until it times out. I can't ping it either. Interestingly, the printer LCD network indicator says it's connected to my wireless network. When it eventually comes back online and I can access the web interface, I still cannot print or scan. This has happened literally (and I mean that, it's no exaggeration) every time I've tried to use the printer. It's never ready when I need it. Last week my father needed to print a document urgently and we gave up trying to get it working, he just went to a local printing shop with his USB thumb drive and had it done there.

I still have a couple of weeks left to return this product to Amazon. Unless I can get a definitive solution within a week I regrettably will have to look elsewhere. I say regrettably because the printer works great when it works.