Free/Busy from onPrem to O365 is working but not from O365 to onPrem
I wasn't able to run the HybridConfigurationWizard successfully (did not work with modern or classic). I did some steps manually
Test-OrganizationRelationship is working from O365. All Steps are successfull (also Step4, Retrieved token for target......)
Outlook Connectivity to onPrem Account: successfull exept last check "Attempting to ping RPC proxy ..." (I'm not sure if this must be successfull)
free/busy O365 to OnPrem(Modern Auth): The Autodiscover service was tested successfully
The Autodiscover service couldn't be contacted by any method
free/busy Lookup failed, https status 504 (Gateway Timeout)
I can see autodiscover requests going through our Firwall and F5 LoadBalancer. In the IIS Log can see a lot of entries and I think the one corresponding to this test has a sc-status of 401 (Unauthorized). cs-username is empty.
Probably an missconfiguration of our F5 but I dont think the Problem is there.
It went through a lot of Troubleshooting Guides without success.
Any help is appreciated.