We have 10 Windows based Dell Venue Pro 11 Model 5130 Tablets that our Customer Service Reps use for internet lookups.  Earlier this month they started disconnecting from the wifi and would not reconnect.  Within 2 weeks time they have all stopped connecting.  Nothing I do seems to allow them to reconnect.

Network Infrastructure -

AP = Cisco Aironet 1600 Wireless Access Points configured with an WPA2 Personal AES Encryption network.

Firewall = Fortinet Firewall/Router - Generic Router Settings

Laptop(control) = Lenovo Thinkpad B50-45 | Windows 7 x64 | Qualcomm Atheros AR956x = Connects to the Wifi normally.(I'm writing this post on the laptop while connected to the wireless network)

Tablets = Dell Venue 11 Pro 5130 | Windows 8.1 Pro | Intel Atom CPU Z3795 1.6 Ghz | Dell Wireless 1532 802.11 a/g/n et al...

Troubleshooting Steps -

Repowered all devices / Including battery removal and fresh boot

Updated drivers - Chipset, and Dell 1538 Wireless

Attempted to update the Firmware.  Firmware Update A02 to A06 was successful.  However Updating to A16 results in the following error popups 

- "Cannot Update a Venue 11 Pro 5130 with a BIOS for a Venue 11 Pro 5130"  

- "Error Unsupported System ID Found. Cannot update a Venue 11 Pro 5130 with BIOS for a Venue 11 Pro 5130"

Obviously the error messages aren't very helpful...  they essentially say that the correct BIOS cannot be installed on the correct System.

I called Dell Support and they suggested an OS reinstall and/or Advanced Hardware Support which I declined. 

I'm hoping there is some software resolution for these issues.  It seems like an issue with the Wireless Driver interfering with a recent Windows update.  I haven't been able to test that theory yet.

My next step is to attempt an OS Reinstall which is difficult due to the Tablet design.  I am also planning to see if System Restore is enabled so that I can roll back to an earlier point to see if the Wireless still works.