iPhone with ios 14. Can't connect to server.

Hello,

  In June, I could use my Skype for Business account on my iPhone to make calls via my work phone number.  Now, I get an error message "Can't connect to server".  I have tried turning off the Auto-Detect Server and inputting https://webdir.online.lync.com/Autodiscover/autodiscoverservice.svc/Root as both internal & external discovery address and have reset the network settings on the iPhone.  I have also uninstalled and re-installed the app.  Any help you can give is greatly appreciated.

Thank you,

Cheryl