Welcome to the community @cleblond
Something is blocking attempt of the ACME http challenge URL. We have seen similar failures caused by a recent change to Palo Alto brand firewalls. They changed a default setting to start blocking acme challenge requests. See more info here
Your symptom is different in that the problem is a timeout rather than "reset by peer" or in some cases a 503 error. These are my test requests to your server. See the problem? While the symptom is different it is worth checking if you have Palo Alto firewall.
(note this has no trailing slash and redirects like other http requests)
curl -I -m10 http://openochem.org/.well-known/acme-challenge
HTTP/1.1 301 Moved Permanently
Date: Wed, 04 May 2022 20:29:58 GMT
Server: Apache/2.4.41 (Ubuntu)
Location: http://openochem.org/.well-known/acme-challenge/
Content-Type: text/html; charset=iso-8859-1
Adding a slash or the Challenge Token results in timeout
curl -I -m10 http://openochem.org/.well-known/acme-challenge/
curl: (28) Operation timed out after 10001 milliseconds with 0 bytes received
curl -I -m10 http://openochem.org/.well-known/acme-challenge/ChallengeFile1
curl: (28) Operation timed out after 10001 milliseconds with 0 bytes received