Jenkins scp plugin - can't connect to server issue, Jenkins scp repositories - can't connect to server, SEVERE: Algorithm negotiation fail

The issue can be resolve, by opening the /etc/ssh/sshd_config file and add the following line:

KexAlgorithms diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1

save and then restart ssh server: service ssh restart.

The problem is fixed.