Aha. When a browser tab is trying to connect to my forum I get a steady stream of these two messages (and it stops when I close the tab, and restarts when I try again in a new tab):
[Thu Dec 28 16:58:21 2023] [authz_core:error] [pid 69145:tid 140002461718272] [client 10.30.9.122:57346] AH01630: client denied by server configuration: /usr/share/httpd/noindex
[Thu Dec 28 16:58:21 2023] [autoindex:error] [pid 69145:tid 140002461718272] [client 10.30.9.122:57346] AH01276: Cannot serve directory /var/www/html/: No matching DirectoryIndex (index.htm,index.php,index.php5,index.php4,index.php3,index.perl,index.pl,index.plx,index.ppl,index.cgi,index.jsp,index.jp,index.phtml,index.shtml,index.xhtml,index.html,index.wml,Default.html,Default.htm,default.html,default.htm,home.html,home.htm,index.js,index.php) found, and server-generated directory index forbidden by Options directive
Does that tell you anything?