I have a Linux machine with OE 11.3 running, using the default ports.
I installed OE 11.4 on the same machine and set it to use port 20934 and adminport 7844, with OEManagement on port 9094.
Up to this point everything works as expected. fuser shows that the expected processes are holding ports 20931, 20934, 7843 and 7844.
I created two databases, through OE Management, but the db agaents fails to start. I get the following in the log:
I FMAGENT15: (14262) Successfully connected to AdminServer on port 8843 using TCP/IP IPv4 address 192.168.69.6.
I FMAGENT15: (8844) Admin Server rejected registration.
I FMAGENT15: (-----) Database for Devl-Koine not found.
Why does it try to user port 8843 when the AdminServer's admin port is 7844?
It seems that 11.3 is also using port 8843.
# fuser -n tcp 20931 20934 7843 7844 8843
Because adminport is for a communication between database plugin and a database and has nothing to do with fmagent/dbagent. That uses as Paul pointed out a different port which can be changed in agent.properties. 8843 is a default value for 11.3. Each release should increment those by 1, but alas 11.4 does not do that. So my guess is that when starting 11.4 the port was busy/used by 11.3 (you should have an entry in ads0.exp and admserv.log of 11.4 about that). And the message "not found" you are getting is due to 11.4 dbagent connection to a 11.3 port and indeed not finding the database there.
Thanks Paul and Libor. This solved my problem.