Home Sharing from Mac - suddenly overnight error message "Failed to connect..."
I have been sharing for years videos and tv series via home sharing from my iMac and MacMini to my AppleTV and iPhone - this worked fine until yesterday. Suddenly (update?) Home Sharing fails from the iMac. I checked the settings (Catalina) and everything seems okay (and was working just some days before) - but now I cannot connect to the iMac home share.
It shows up in the overview of e.g. the TV app on the iPhone along the MacMini share - but when selecting the iMac home share I get "Failed to connect. Please check your network and try again". Sharing from MacMini works. Also access from AppleTV or MacMini to the iMac fail. Any ideas?
iMac Pro, macOS 10.14