Hello,
I am Prosenjit, an expert in AWS, Azure, VMWare and Multiple Microsoft Technologies. As you want to learn more about Windows Server Administration, I would suggest you to focus on Server 2016 as this is the latest Server OS from Microsoft and all the enhancement of the next Server (Server 2019) would be based on this.
I have been working with Microsoft Windows Server since 2007. I started with NT and now works with 2016 :) I have some study material as well, which I can share with you, also I will encourage you to go through MVA courses on Server 2016.
I will be able to guide you over email / Skype sessions. This is a placeholder bid, let's connect to discuss further and identify the key areas you want to learn.
Best regards,
Prosenjit SEN