Exchange 2019 Outlook Not connecting

Hi,

I have migrated all mailboxes from exchange 2016 to exchange 2019. Shutdown 2016, but outlook 2016 still trying to connect to old exchane 2016 Server.

If i do a outlook email connectivity test it shows old MAPI URL. If I do another test It shows New one. I am confused how it is getting old mapi url even though the server is shutdown. Need your valuable assistance. My autodiscover url is same for both old and new server.