Problem with opening attachment in calendar appointment

Good afternoon all,

i have question about appointment in calendar with attached files. I still getting error 401 unauthorized acces , but when i try the same in web mail i got no error. Is this problem related to settings of our mail server ? Em client version is 5.0.12763

Thank you for your time.

can you please send me the problematic event saved in .ics format? Attach the URL of your CalDAV server too. Thank you very much.