Hi. 🙂 If you want to upgrade your unsupported Lumia to latest 1709 redstone 3 build then just follow these steps
Note: don't use registry providers for this interop tools version just use 'This device'
Make the edits
Go to Registry Browser
HKLM\SYSTEM\Platform\DeviceTargetingInfo
PhoneModelName: Lumia 950 XL
PhoneHardwareVariant: RM-1085
PhoneManufacturingModelName: RM-1085_15217
Check for updates. There should be available 👍🙂
