Could this be it? Resolving the "Unknown Device" in device manager of a Dell Venue 11 (7130/7139) tablet 

Thanks NJDave, that particular driver has already been installed with no improvement.

The Dell Wireless 1537 Wi-Fi and Bluetooth driver has also been reinstalled. Wireless works, however, Bluetooth is no longer functional on the tablet and perhaps the "Unknown Device" relates to Bluetooth.

On the support website there are actually two sets of Wi-Fi/Bluetooth drivers (one set being the combo driver you installed), plus a "Bluetooth application." I don't know whether the application is necessary for Bluetooth to work, or if the device is even defined as yet.

A quick Google search (which I should have run last time) indicates the device(s) correspond to a serial communications device, whose driver is probably part of the more general chipset driver. This device may or may not be related to Bluetooth. Maybe it's just part of the chipset and not connected to anything? For diagnostics? Hard to say; it may not mean anything for day-to-day operation.

Before getting deeper into it, have you tried running the "Dell Update Application" that's on the support website? I'm guessing that's similar to Dell SupportAssist that runs on newer platforms and tries to ensure you have all the necessary drivers installed and updated. Heck, you might try running SupportAssist as well, if Dell Update doesn't work. That'd be the next step I'd recommend.

Hi,

I tried installing the Bluetooth drivers, no improvement.  SupportAssist indicates up to date.

I neglected to mention you shouldn't post your private service tag here (the admins will likely remove it), but since you did... I fed it to the Dell OS Recovery Tool, which says it'll provide a recovery image with Windows 8. I bet if you were to go that route, and then upgrade to Windows 10, all the necessary drivers would be there, but that's time-consuming and seems kind of sloppy (and Windows 8, yuck). Still, as a last resort, it could be worse.

The mystery device(s) do seem to be the Intel Serial I/O Host Controller. Since there's no specific driver for this on the support website, for Windows 8.1 or Windows 10, the driver is probably part of another package. Perhaps it's in the Intel chipset driver (which should really be installed, if you haven't) or perhaps it's part of the Intel Management Engine package (for corporate platform management). Intel has a driver for what seems to be this device, but it's a generic driver and there could very well be Dell-specific customizations. There's also the Intel Driver & Support Assistant which checks your hardware and updates it to the latest generic drivers; maybe it will find something.

As for Bluetooth... what does Device Manager say the device is? Is there a specific driver installed, or a Microsoft driver...? Have you kept track of which drivers got installed from Support Assist or manually?

The Device Manager does not show Bluetooth. So I will proceed to use the Recovery procedure.

However, the Recovery site is unable to connect to the backend to download the image.

I'll try later on today.

A lot of people have been reporting that problem. At least one user reported success after explicitly allowing the recovery tool through Windows Firewall.

Sorry you have to go through the Windows 8 rigamarole, but I get it. Especially for non-desktop systems, let alone an oddball Windows tablet, once a couple of generations of OSes have passed it can be really difficult to find drivers. Assuming it works and you get Windows 10 working, I'd do a disk cleanup to remove all the Windows 8 files and then get an image backup, so you always have an easy way to recover your system.

Dell OS Recovery Tool is still unable to download the recovery image.  I have included the app within Windows Firewall, but still getting "We are currently unable to connect to the backend."

How can we contact Dell to report this issue?

Send a private message (envelope icon upper right, next to your avatar) to @DELL-Cares .

I tried myself, and the Win 10 image for my desktop started downloading immediately, but the Win 8 image for your tablet failed with the same backend error. Obviously an issue at Dell.