Make sure you don't have a firewall (or similar) blocking external traffic to port 1311.  Re-run the OMSA setup, choose Custom, and make sure that the Web Server (AND ALL SUBFEATURES) is installed.  If not all of the subfeatures are installed, you won't have external access to the webserver on which OMSA runs.  If it doesn't list "web server" in the list of features to install, make sure that ALL features that are checked have ALL subfeatures selected.
I have OpenManager Server Administrator installed on two different servers. One is a Poweredge2800, Windows Server 2003 R2, Standard Edition, SP2, running OMSA 5.4.0.  I can log into it locally on the server and also through a browser, connecting through the address [URL] The other is a Poweredge2900, Windows Server 2008, Enterprise Edition, SP1, running OMSA 5.5.0.  I can log into it locally on the server but I can't access it through a web browser.  In IE I get the message "Internet Explorer cannot display the webpage".  I am connecting using the following address [URL]   I have installed Web Server (IIS) Tools thinking that would give me access.  It didn't. Any suggestions on what I am missing?
OpenManager Server Administrator