Trapped in Exchange Server 2016 RTM. How to update?

Is there another site that deals with Exchange Server questions? There doesn't appear to be much activity here.

Thanks for that link, Dan.

To begin, here is information I found earlier, related to upgrading from Exchange Server 2016 RTM to the most-recent CU23.
https://www.alitajran.com/update-net-framework-exchange-server/#h-exchange-server-2016

As I mentioned in my first post here, and according to the above link, I cannot update Exchange Server 2016 RTM, to CU23 without doing so in steps. The first update step (according to the chart) requires CU4 which I can no longer download from Microsoft. Please scroll down to the Exchange Server 2016 update chart (in the above link), to see the steps required (according to that site).

However, if I understand what is said in the link which you provided late last week, (https://docs.microsoft.com/en-us/exchange/plan-and-deploy/supportability-matrix?view=exchserver-2019#microsoft-net-framework and then scroll down to Exchange 2016 chart), our currently installed .NET Framework Version 4.8 is NOT supported for the Exchange Server 2016 RTM which is indeed running, and yet it appears to be working correctly.

Given that we have .NET Framework 4.8 installed, can I update from Exchange Server 2016 RTM, all the way to 2016 CU23 in one step, or do I have to step up through CU4, then CU9, then CU12, then CU14 and finally CU23? (Reminder...I can't download CU4 or CU9 from Microsoft).

Thanks for whatever assistance is offered.