You only need the
sshd service running on one machine, the machine you wish to connect
to (unless you really need to make ssh connections both ways).
If the SSH server is running ok then on the other machine, the machine you wish to connect
from, you open an sftp connection like this:
sftp user@host.domain
Does this work? If not, what error?
To check that SSH itself is working, open a shell connection from the client machine to the server like this:
ssh user@host.domain
Does this work?