I found a solution for my problem:
I deleted the keepalive command from the “vpn_start”-file and added in the command line:
–ping 10
–push ping-exit 25
If Client A connects and Client B afterwards, only Client B will receive the ping from the Server every 10s. Client A gets no more pings an disconnects himself.
Additionally i found out:
If you are in use of user-specified file in the ccd-directory and have an “inactive” command this will not be affected by these changes.
thank you redfive for the essential hint 😀