A master should never have a parentname in its relay.ini. The first thing to do is to stop the service of the master then delete that parentname and anything that is set on "sequence=". Then restart the master.
You say you are able to telnet on the port 1610 and on the port 1611 from the client to the master? If so, please check if "PAC=" and "SSL=" are set to the same value in your client and your master ../config/mtxagent.ini.
Have a good day
You should recreate the zip of the log files where both log files contains the same time stamp (client is from 20.6 and master is from today) and please add the mtxagent.ini from your client.
You wrote the the ip address of your master server is 192.168.4.168 as in the provided master.log file the master ip address is 192.168.51.50. Does the master server have multiple NICs installed?
Based on the master.log file it looks like there are issues with the SSL certificate:
2015/07/11 22:47:08 Server I  Received incoming connexion (TCP (local: 192.168.51.50:1610, peer: 192.168.51.1:51610)) of priority 1: handling at once
2015/07/11 22:47:08 Server I  Processing connection TCP (local: 192.168.51.50:1610, peer: 192.168.51.1:51610)
2015/07/11 22:47:08 Server I  Connection is secured
2015/07/11 22:47:08 Socket D  BufferedSocket: receive failed
2015/07/11 22:47:08 Socket D  SslHandshake - Fatal error (SSL_ERROR_SSL)
2015/07/11 22:47:08 Socket D  SslHandshake - Error details (error:14094412:SSL routines:SSL3_READ_BYTES:sslv3 alert bad certificate)
2015/07/11 22:47:08 Server W  SSL handshake failed