Hi Plamen!
Thanks for your fast reply!
The problem occured the special, hard security SSHD setting on Linux servers:
MaxStartups
"Specifies the maximum number of concurrent unauthenticated connections to the SSH daemon. Additional connections will be dropped until authentication succeeds or the LoginGraceTime expires for a connection. The default is 10:30:100.
Alternatively, random early drop can be enabled by specifying the three colon separated values “start:rate:full” (e.g. "10:30:60"). sshd(8) will refuse connection attempts with a probability of “rate/100” (30%) if there are currently “start” (10) unauthenticated connections. The probability increases linearly and all connection attempts are refused if the number of unauthenticated connections reaches “full” (60)."
The setting was maximum 2 concurrent unauthenticated connections.
If increase to 3, the convert job run successfully (tested repeatedly).
It seems that the convert job (converter server, 2 * HelperVM) open more concurrent SSH connection to source server at same time, and the third connection closed by remote host (source server).
The only problem, that the error message was not helpfull and I can't see any reference to the concurrent SSH connections in the converter documents.
Anyway thanks again your fast reply!
Regards,
nower