TC70 WiFi Connection Drops

We have 18 TC70 units and constantly having WiFi issues with them. Even though the WiFi signal bar seems ok and good reception, sometimes apps, browsers stop responding because of connection issues. I opened a command prompt from a windows machine and have it constantly keep pinging one of the devices, and even when the unit was responding all the ICMP ping requests, the apps that do network traffic running on the devices keep freezing. Any suggestions?