I sounds to me that there is something as @WadeAlsup said that is changing when the device leaves the cable and hops on the wifi. I would venture to guess it is in these areas.
1. Is there an IP route between the endpoint and the network drive server, do a basic ping test.
2. Is there DNS resolution on the wifi for the network drive server.
3. See the screenshot from Wireless > Access Control, make sure your wireless clients are a part of the LAN.
4. See other screenshot from Wireless >Firewall..., we deny this but you need an allow here.