Copy the old_key from connect bot then convert by:

“openssl rsa -in old_key -out new_key”

import the new_key file into Solid Explorer and that one will work.
That new private key will start with
—–BEGIN RSA PRIVATE KEY—–
and ends with
—–END RSA PRIVATE KEY—–

Source: SSH key not working – Solid Explorer 2.0 support forums

Source: django – Where do I copy my VirtualHost directive in my Apache docker image? – Stack Overflow