After contacting Oracle support, I've -kinda- been able to figure out what was going on. This server has 4 network adaptors, 1 adaptor connected to the network, and 3 unconfigured adaptors connected to an iSCSI storage. The problem seems to be caused by the web-client, or EM server (not sure here) trying to send the webpage request to the wrong adaptor.
For anyone facing the same issue, you can check this by browsing to the URL (using the hostname.domain) and then checking the listener.log file (-oracle_base-/diag/tnslsnr/-instance-/listener/trace/listener.log). For me, in the error message a different IP address than the servers main network adaptors IP address was shown. The IP address of one of the network adaptors connected to the iSCSI where shown. When omitting the IP addresses in my original post, I didn't spot this IP address difference.
18-DEC-2015 14:17:04 * http * (ADDRESS=(PROTOCOL=tcps)(HOST=<NOT SERVER IP address!>%14)(PORT=62119)) * handoff * http * 12518
TNS-12518: TNS:listener could not hand off client connection
TNS-12560: TNS:protocol adapter error
When disabling the additional network adaptors, everything works fine.
Additionally, when going to "chrome://net-internals/#dns" in chrome, the IP addresses of all four network adaptors showed up for my hostname.
Apparently, this problem -does not- happen, when browsing to the webpage from another host. Also, nslookup returns only the correct IP address. So it seems this is not a DNS issue, but a local issue. I think this is not a full answer to the problem, as disabling network adaptors can't be a final solution, but I hope anyone facing this issue in the future has "more to go on" now...
Where does the discrepancy between IP address returned by the DNS server, and the IP addresses used by web browsers come from?
I've also made some additional changes that might have influenced the end-solution, so for completeness I'll include them. Not sure if relevant...:
- Increased processes parameter of the database from 300 to 1000
- Altered the "dispatchers" parameter by adding "(DISPATCHERS=5)"
Best Answer
What makes you think that the web site is being offered on port 5500?
I don't know about the Express version, but full-blown Enterprise Manager is provided by a running, Middleware process. Is there a Window Service that you need to start (or, for whatever reason, has failed to start?)
That's because the Database and the Web Site that you use to manage the Database are two completely separate things.