Only functioning after restart jicofo

Tried to install on ubuntu 18.04/nginx as well as debian 10/nginx.
In both cases: participants show up without video/audio (the chat function okay). They can only see themselves.
After a new installation system functions only after a restart of jicofo. But: same problem occurs when trying a new/second conference session. But: then no restart of jicofo is possible anymore: “Job for jicofo.service failed because the control process exited with error code.”
See “systemctl status jicofo.service” and “journalctl -xe” for details.
In status:
● jicofo.service - LSB: Jitsi conference Focus
Loaded: loaded (/etc/init.d/jicofo; generated)
Active: failed (Result: exit-code) since Mon 2020-06-15 13:08:57 CEST; 50s ago
Docs: man:systemd-sysv-generator(8)
Process: 13714 ExecStop=/etc/init.d/jicofo stop (code=exited, status=0/SUCCESS)
Process: 14584 ExecStart=/etc/init.d/jicofo start (code=exited, status=2)
Tasks: 104 (limit: 105)
CGroup: /system.slice/jicofo.service
└─13306 java -Xmx3072m -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/tmp -Dnet.java.sip.communicator.SC

jun 15 13:08:57 eu-ist.eu systemd[1]: Starting LSB: Jitsi conference Focus…
jun 15 13:08:57 eu-ist.eu systemd[1]: jicofo.service: Control process exited, code=exited status=2
jun 15 13:08:57 eu-ist.eu systemd[1]: jicofo.service: Failed with result ‘exit-code’.
jun 15 13:08:57 eu-ist.eu systemd[1]: Failed to start LSB: Jitsi conference Focus.

Question: where can I change this exit code?
Advice in advance section installation guide do not change anything. Server not behand NAT.
Thanks in advance for every advice.