It works for me, I can’t reproduce the problem, I get redirected to port 980 when going to server-manager.
Do you have any error in httpd logs (access.log and error.log)?
The only thing in error is this (because I have no custom index page):
[Thu Nov 24 21:27:27.785555 2016] [autoindex:error] [pid 7140] [client 66.249.75.185:40276] AH01276: Cannot serve directory /var/www/html/: No matching DirectoryIndex (index.html,index.php) found, and server-generated directory index forbidden by Options directive
Not really a big problem to not get this fixed, as I can access it directly from the 980 port even when I am away from home, but I typically try to run most pages and programs on my servers in a subfolder. Less ports open, less risks with intrusions etc.