Airport Express Issue...Help!

I connected an Airport Express to a 8 port hub (hard wired) in our church sanctuary in order for people to be able to access the internet wirelessly. Everything works fine until a couple of days go by and the AE appears to not be connected to the internet somehow. It still broadcasts a wireless signal but will not let you access anything. The fix is I have to go in and unplug the AE and plug it back in and then it works fine...until a few days later. Any ideas? Surley it's a setting that I am missing.