Dr. Solo,
If you would like assistance jumping from Windows Server 2012 R2 to Windows Server 2019, you'll find my rates most reasonable. I can also get you very reasonable hardware and licensing for Windows Server 2019. For 2012R2, we are in the extended support period where only security fixes are made to the OS.
-- Mainstream Support First Five Years: Security and bug fixes.
-- Extended Support Last 5 Years: Security fixes only.
For workstations, keep them updated as much as possible since that is where end users are involved. Also, to ensure stability, make certain all line-of-business software installed is less than 5 years old. That 2009 version of Adobe Standard and copy of Office 2010 isn't doing you any favors. Lastly, make certain only the software you need is installed. Get rid of the trial version of QuickBooks and what-have-you that came with the machine if you bought it retail.
Oh, and run one AND ONLY ONE antivirus. Don't have Norton, This defender, and that Defender, and all the others installed and running at the same time.
JamesNT