On the client side, add the following to `.ssh/config`:

 HostKeyAlgorithms=+ssh-dss
 KexAlgorithms +diffie-hellman-group1-sha1,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1
 PubkeyAcceptedKeyTypes +ssh-rsa

or 

 PubkeyAcceptedAlgorithms +ssh-rsa

I'm not sure what impact this has on security.