Coincidentally, Ive been looking at online training options re Windows 2016 Server. At the time of writing, Udemy have another 4-5 hours of 'sale', with many courses that were c £200 recently (I was looking a while) now only < £20.
Alternative, and I imagine upmarket, to Udemy are official Microsoft Training Providers such as Learning Tree and QA Training which both offer in-person training and, more recently, an online version of their courses with real-person support, which you don't get so much of at Udemy, etc.
My needs are likely very different to yours but I have been looking at courses that relate to specific Microsoft exams/qualifications. In case you are not already familiar with the Server 2016 ones (to the best of my, inexperienced, knowledge) for a less-advanced professional are 'Installation, Storage, and Compute with Windows Server 2016', Exam 70-740; Networking with Windows Server 2016, Exam 70-741 and Identity with Windows Server 2016, Exam 70-742. Passing these exams leads to a qualification - Microsoft Certified Solutions Associate (MCSA).
If your employer depends upon your knowledge, skills and understanding then they will benefit from you having the best training. In my view, that is likely to be from an in-person course such as Learning Tree provide. When they discover it is c £2,000 for 5 days they may change their mind. It's still true, though. Professional development is as important as hardware and software. The online equivalent courses seem to be about £600, allowing you three months to cover the same material with access to an online tutor.
If you read this in time - buy a couple of the Udemy courses for yourself at the 90% off rate. (If anyone has worked out when these offers are timed, please let the rest of us know!).
Here are some links from windows I happen to have open still, in case they help:
Complete Windows Server Certification Guide: MTA, MCSA and MCSE
https://blogs.technet.microsoft.com/uktechnet/2017/06/30/complete-windows-server-certification-guide-mta-mcsa-and-mcse/
Installation, Storage and Compute with Windows Server 2016 (20740) from Learning Tree, in-person or online
https://www.learningtree.co.uk/courses/8401/windows-server-training/
Microsoft MOC On-Demand courses from QA
https://www.qa.com/training-courses/technical-it-training/microsoft/microsoft-on-demand
All Microsoft Certification exams
https://www.microsoft.com/en-us/learning/exam-list.aspx
These are the Udemy courses that I was looking at - I cannot say if they are any good as I haven't signed up. At the time of writing they are all reduced from c £200 to less than £20 and, as I recall, they really were £200 recently. Of course, maybe I was completely naive to even consider them at that price!
Installation Storage & Compute with Windows Server 2016 IT certification course (aimed at Microsoft 70-740)
https://www.udemy.com/microsoft-70-740-install-storage-compute-w-server-2016/
Server 2016 Exam Prep: 70-740 -Installation and Storage (just practice tests)
https://www.udemy.com/server-2016-exam-prep-70-740-installation-and-storage-n/
Active Directory with Windows Server 2016: The Total Course
https://www.udemy.com/active-directory-with-windows-server-2016-the-total-course/
Microsoft Windows Server 2016 Certification (70-741)
https://www.udemy.com/microsoft-windows-server-2016-beginner-to-expert/
MCSA Windows Server 2016 (70-740) Course
https://www.udemy.com/mcsa-windows-server-2016-70-740-course/
I hope this helps you but it would be better still, for me, if someone with more experience could chip in.
Cheers
Ian