There has been times when access points drop off the network for many hours then reconnect without any intervention. We have found out that it is a DNS problem with the pointer to wifidog.coffswifi.net server. It has a dynamic address and used no-ip.com. So every time a new address was allocated some access points would drop off until their providers DSN servers where updated. It now has been fix - we have a static ip now so there should be less dropouts.