SuuntoLink + DM5: Fixing Core Isolation Issues with Suunto's USB Drivers

[yetanotherdeveloper]

If you’ve stumbled upon this post, chances are you’ve tried to get your Suunto watch connected via SuuntoLink, only to be greeted with an error message, a Code 39 in Device Manager, or Windows outright refusing to run the driver.
The reason is that Suunto’s drivers are stuck in 2015 like a bad time capsule.

The Problem:

When Core Isolation is enabled in Windows Defender, SuuntoLink fails to recognize the watch and instead tells you to “install” it—like we haven’t already done that a dozen times.
Root cause? A part of the Suuntos USB driver is not certified and thus it is not safe for use.

Suunto uses an FTDI driver for a serial adapter and a port adapter to communicate with the watch. But since they never update anything, we need to fix it ourselves.

The Fix:

1. Install Suunto’s ancient, decrepit drivers (yes, we need them first, unfortunately).

2. Get the latest FTDI drivers

   • Head over to the FTDI Chip website
   • Navigate to Drivers -> D2XX Drivers
   • Scroll to the table and download the latest version for Windows (NOT the executable!)
   • Unzip the folder somewhere accessible.

3. Delete the Suunto FTDI Bus Driver

   • Open PowerShell as Admin
   • Run pnputil /enum-drivers and look for the Suunto driver with ftdibus (NOT the port version) from 2015.
   • Note down the oem name (e.g., oem11.inf).
   • Run:

     pnputil /delete-driver <NAME> /uninstall /force
     

     (Replace <NAME> with the actual oem file, e.g., oem11.inf)

4. Install the Latest FTDI Bus Driver

   • Your driver will now look broken in Device Manager. Perfect!
   • Open Device Manager and locate Universal Serial Bus controllers.
   • Find USB Serial Converter (it may have a warning icon next to it).
   • Right-click on it and select Update Driver.
   • Choose Browse my computer for drivers.
   • Click Let me pick from a list of available drivers on my computer.
   • Click Have Disk….
   • Navigate to the unzipped FTDI driver folder and select ftdibus.inf.
   • Click OK, then select USB Serial Converter.
   • Click Next, Close, and restart your computer.

The Outcome:

Now, your SuuntoLink might still throw occasional tantrums, but at least your driver will work. Congratulations, you’ve done the job.

Suunto, if you’re reading this, update your USB drivers.

Good luck!