Ok the client mode ist working and i can access shares on other devices.
But the sever gives me a strange problem. Target is to share a folder (/mnt/mmcblk0p2/extern) for all users in the network rw without password. No windows clients in the network - only linux and android. I created a smb.conf file with the entries:
[data]
path = /mnt/mmcblk0p2/extern
read only = no
guest ok = yes
The folder has 777 and samba reporting misconfigured "server role" and exits.