ssh: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1
If you run into a key exchange issue with ssh it probably means the server you are connecting to has an older cipher.
To fix a diffie-hellman-group1-sha1 problem try the following command:
ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 “server-ip”
You can do the same thing with other ciphers by replacing diffie-hellman-group1-sha1 with the offending cipher type.