This is certainly an odd situation. Here are a couple of things you can try:
1. Replace the hostname in the UNC path with the IP address of the host that you are attempting to access.
2. If you are attempting to connect to a multi-level UNC path, try only connecting to the base share.
3. Check to see if NetBIOS is enabled on the AP.
Here is a question:
How does the AP connect to the wired network?