Airport Extreme Oddness

I've having a very odd problem and I think it's with my airport extreme. It started last night when I tried to print to my wireless HP printer and was told the printer wasn't found. However, I could find the printer in the control panel but when I tried to re-add the printer I just got an error.

Then my NAS, which is connected to the Airport via Ethernet went offline - couldn't be found. And slowly over the past couple of days all my Nest alarms and thermostat have lost the wireless connection and I can't get them re-added. The weird thing, though, is that the internet seems to be working find through the Airport - I'm using it right now. I've tried restarting the base station several times and de-connecting / re-connecting the items connected to the unit via ethernet but it doesn't seem to be working.

Has anyone ever experienced anything like this before ? Usually a peripheral either works or it doesn't, this thing seems to be half-*** working and I'm at a loss.