Troubleshooting calendar sharing on Exchange / Office 365 hybrid

Firstly create a test user in our Exchange environment e.g.:

cd "C:\Program Files\Microsoft\Exchange Server\V15\scripts"

or for Exchange 2010:

cd "C:\Program Files\Microsoft\Exchange Server\V14\scripts"

./New-TestCasConnectivityUser.ps1

and test calendar connectivity with one of your client access servers with:

Test-CalendarConnectivity | FL

and also check it is enabled on the OWA virtual directory with:

Get-OWAVirtualDirectory | Select Name, Server, Calendar*

Check WSSecurityAuthentication is set to true on both sides:

Get-AutodiscoverVirtualDirectory | fl name, server, *url, ExternalAuth*, WSSecurityAuthentication

Ensure that the organizational relationship is setup correctly:

Get-OrganizationRelationship | Select Identity, Name

Test-OrganizationRelationship -UserIdentity [email protected] -Identity "Office 365 to on-premise" -Confirm -Verbose