Hi Johan,
The issue you get is related to you AD configuration and your client workstation. Did you check the output of the "klist" on your client? Did you check if you have duplicate on your AD with the command "setspn -Q "Your SPN" ? Did you have a multiple domains landscape and you have only configure the keytab for the parent domain and not the child domains in ABAP transaction "spnego"?
KR
Valerie