your question is a bit vague -
try this on both machines first -
<path to ssh>/ssh -V
once you've figured out version, you can start testing like -
ssh -l <user> <system>
if you're trying to do this as root, you've got changes in the sshd_config file you need to make, but let's get the basics addressed first - jeff
you're right, the default version of ssh installed on 8/9/10 points to /etc/ssh/sshd_config for the server daemon config, and ssh_config for the default user config -
if you're running openssh or some other version, there are a LOT of places that could reside in other than /etc, such as /usr/local/etc, /opt/ssh/etc, /opt/SFW/..something.../etc...
getting the versions determined first will help direct us how to help you connect -
also knowing what users are in the equation helps - jeff