Windows End of Support Calendar
The below End of Support Calendar shows all Microsoft Operating Systems end of support dates, whether they are the end of mainstream support that updates features and cosmetic changes or extended support, which ends security fixes and all Microsoft technical support other than old web pages.
Windows 10 version 1709 End of Extended Support
(Date is approximate)
Windows 10, version 1709, is also known as Build 16299, and was the "Fall Creators Update" to Windows 10. After Extended support ends, there will be no more security patches to this version of Windows.