WiFi Disconnecting

I have multiple Pis running MusicBox, all on RC7 now. The hard-wired ones are mostly fine, but every one using WiFi, whether built in or a USB adapter, drops off the network periodically. As a test I had my network automatically reboot at 3am and that causes them all to drop and they don’t reconnect until I reboot the pi, even though the network is only down for a minute or two. Even without having the network reboot nightly the WiFi Pi’s all eventually drop off, it’s like they won’t reconnect after WiFi is dropped. What am I missing?