On-Premise Users cannot see Free/Busy for O365 users

[MrSysAdmin]

Hi i have Exchange Server 2016 CU 20 Clasic full hybrid env

in outlook, On-Premise Users cannot see Free/Busy for O365 users.

in OWA its works fine.

i checked  Microsoft Remote Connectivity Analyzer and i got this error:

https://drive.google.com/file/d/1IbZ017Yn0_lEJe-8w_G4xsMJB-Es6_Pm/view?usp=sharing

[#2 · Accepted solution]

Please see this post : https://techcommunity.microsoft.com/t5/exchange/tls-1-2-is-coming-to-exchange-on-premises-using-hybr...
My company had the exact same problem 2 months ago

[#3]

thank you