Hi all,
Currently running Exchange 2013 - 3 node DAG (2 on site - 1 dr site).
Since updating to applying the following update we have seen a marked drop in performance from the servers and users are reporting that their overall experience has dropped considerably.
Security Update For Exchange Server 2013 Cumulative Update 23 (KB4536988)
Servers were originally on CU15 upgraded to CU21 pre December, no issues. Completed the step upgrade between CU21 and .net to get to the correct levels - .net is currently 4.7.2
Once the update was completed we did have the ECP / OWA issues listed in the below article, applied the fixes and no problems there, just the bad performance
https://borncity.com/win/2020/02/15/exchange-server-2013-mail-issues-after-update/
Examples include Outlook dropping connecting, taking increasing time to access folders and mailboxes
Two servers @ primary site with DAG, majority of users are connecting in through Citrix with mailboxes in online mode.
Checking the CAS load its appears to only be reporting that a since server has any connections.
Any advise would be appreciated.