Teams Calendar App test now available in Microsoft Remote Connectivity Analyzer

Hi ThorstenK2 

Thank for your feedback. EWS and Rest URL/endpoint are cached by Teams middle tier service. This means Exchange autodiscoverV2 lookup is not performed on every single call preventing exposing additional info from backend. Requests from teams middle tier have specific user agent value 'User-Agent: MicrosoftNinja/1.0 Teams/1.0 (ExchangeServicesClient/0.0.0.0) SkypeSpaces/1.0a$*+' so youc an trace external requests (eventually using IIS failed request tracing) and confirm if they make autodiscover and EWS. If they don't even make Exchange / reverse proxy please review firewall exclusions. If they make Exchagen on-premises but forbidden 403 is returned confirm if oauth was properly configured by running Test-OAuthConnectivity. Last but not least confirm if issue is affecting all users or only a subset as that can eventually be a caching issue if mailbox was recently moved (last 3 days). If these suggestions still don't help and support case still not resolved please provide me support case ID and I can help addressing this issue.