Error similar to…
Unable to negotiate with x.x.x.x port 22: no matching key exchange method found. Their offer: diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1
Two things:
1) Add the following argument to the ssh command:
-oKexAlgorithms=+diffie-hellman-group-exchange-sha1
2) Add option to your ~/.ssh/config:
Host x.x.x.x
KexAlgorithms=+diffie-hellman-group-exchange-sha1
Other options that might be relevant include HostkeyAlgorithms
and Ciphers