strange file sharing behaviour

Hi

im having a macmini with 10.11.4 / Server 5.1 running.

In principle everything is fine. Except filesharing is strange.

In the Finder of my MacBook (also 10.11.4) i can see the macmini in the sharing section.

Once i click on the macmini it tells me connectivity failed. If i click "connect as" it also tells me connection failed.

If i use the Menue "connect to server" : afp://macmini or smb://macmini i get a selection box for the shared folders and i can mount the folders.

Any idea ?

On the MacMini the console shows the following for the failed attempt:

4.05.16 14:47:37,127 digest-service[31900]: label: default

04.05.16 14:47:37,127 digest-service[31900]: dbname: od:/Local/Default

04.05.16 14:47:37,127 digest-service[31900]: mkey_file: /var/db/krb5kdc/m-key

04.05.16 14:47:37,127 digest-service[31900]: acl_file: /var/db/krb5kdc/kadmind.acl

04.05.16 14:47:37,134 digest-service[31900]: digest-request: uid=0

04.05.16 14:47:37,137 digest-service[31900]: digest-request: netr probe 0

04.05.16 14:47:37,138 digest-service[31900]: digest-request: init request

04.05.16 14:47:37,162 digest-service[31900]: digest-request: init return domain: MACMINI server: MACMINI indomain was: <NULL>

04.05.16 14:47:37,163 digest-service[31900]: digest-request: uid=0

04.05.16 14:47:37,163 digest-service[31900]: digest-request: init request

04.05.16 14:47:37,189 digest-service[31900]: digest-request: init return domain: MACMINI server: MACMINI indomain was: <NULL>

04.05.16 14:47:37,189 smbd[28628]: Client requires signing while bound to unauthenticated Directory Service

04.05.16 14:47:39,003 apsd[77]: Unexpected replacement of connection in <APSConnectionServer: 0x7fc5b050bbf0>

04.05.16 14:47:40,647 digest-service[31900]: digest-request: uid=0

04.05.16 14:47:40,648 digest-service[31900]: digest-request: init request

04.05.16 14:47:40,675 digest-service[31900]: digest-request: init return domain: MACMINI server: MACMINI indomain was: <NULL>

04.05.16 14:47:40,686 digest-service[31900]: digest-request: uid=0

04.05.16 14:47:40,686 digest-service[31900]: digest-request: init request

04.05.16 14:47:40,710 digest-service[31900]: digest-request: init return domain: MACMINI server: MACMINI indomain was: <NULL>

04.05.16 14:47:40,714 digest-service[31900]: digest-request: uid=0

04.05.16 14:47:40,809 digest-service[31900]: digest-request od: ok user=MACMINI\user proto=ntlmv2 flags: ENC_128, NEG_VERSION, NEG_TARGET_INFO, NEG_NTLM, NEG_TARGET, NEG_UNICODE

04.05.16 14:47:42,479 com.apple.xpc.launchd[1]: (com.apple.collabd.preview[31905]) Service exited with abnormal code: 1

04.05.16 14:47:49,271 kdc[94]: DSUpdateLoginStatus: Unable to synchronize login time for diradmin: 77009

04.05.16 14:47:49,499 kdc[94]: DSUpdateLoginStatus: Unable to synchronize login time for diradmin: 77009