Exchange 2016 CU23 breaks Outlook 2010 connection

Hello,

I have an environment with an Exchange 2016 CU22, that connects to a public folders in legacy, which resides on an Exchange 2010.  We have many users still using Outlook 2010 and all is working fine.

Yesterday we decided, to my great regrets, to install CU23 and a nightmare began, Outlook 2010, on the first start since CU23, connects no issue, but if we close Outlook then reopen it, no more connections, it just shows disconnected and if I look deeper, I see it just keeps retrying but Exchange refuses it to connect.  I looked everywhere in the CU23 documentation for changes and nowhere there is mention about Outlook versions and legacy connections being affected by it!

Anything I can do to get Outlook 2010 going again?  What happened on the first connection, what did Exchange tell Outlook to reconfigure?  Newer Outlook works fine.  All Outlooks connect with RPC because of the legacy public folders.