Microsoft has released Security Updates (SUs) for vulnerabilities found in:
Exchange Server 2016
Exchange Server 2019
SUs are available in a self-extracting auto-elevating .exe package, as ...
Updated Jun 13, 2023
Version 1.0
Blog Post
The Windows offered functionality "Network Load Balancing" (NLB) is not supported anymore by Microsoft since -as far as I remember- Exchange 2010 SP3+.
This was an just "not recommended and not supported anymore", now it is an "not taken care anymore" due i.e. architecture change. There are lots of articles describing this. If you continue using NLB it is at your own risk. No wonder that with some security packs today NLB (after many years) will stop working.
Please use DNS-RR or Loadbalancing by real Load Balancers.
Rolling back security patches is not the solution at the end. DNS-RR works fine with nearly all applications (especially Outlook). I experienced one App that had problems; SAP. They maintain there own ARP Cache or HOST Files or DNS Cache or whatever. As soon as these are resettet, also SAP will work fine with DNS-RR, als long as DNS is getting an update for the CAS of the Exchange Sevrers for some reason.