RE: U2312HM, Lenovo, Windows 10 update caused issue
"After some Win10 updates my Dell monitor stop works as 2nd Display with laptop Lenovo Yoga."
From a supported/tested operating system point of view, Microsoft is correct. Dell never validated the 5 year old U2312HM with Windows 10. My point was that even though not validated by Dell for Windows 10, the U2312HM and cabling were working with Windows 10 PRIOR to the latest update/push made BY Microsoft. So they did push some driver onto your computer that broke the connection chain.
Social Media Support
Run the PC pre-Windows diagnostics
Where do I find my Dell PC Service Tag or Express service code?
Out of Warranty Support