Richard I saw your tutorial but when I go to command:
./letsencrypt.sh request_single myhostname (I have replaced by my hostname) 4096
returns:
Error: http://myhostname/.well-known/acme-challenge/letsencrypt_1586193088 is not reachable. Aborting the script.
dig output for myhostname :
Please make sure /.well-known alias is setup in WWW server.