[SR-Users] rtpengine: Failed to open UDP control connection port

Hello,

We're using Kamailio 4.2.1 with rtpengine 5.1.2.1 on Ubuntu 16.04. When running rtpengine we get this error:

[1500263405.711288] ERR: FAILED TO CREATE KERNEL TABLE 0 (File exists), KERNEL FORWARDING DISABLED [1500263405.712367] CRIT: Fatal error: Failed to open UDP control connection port

The first line I think is not important, but the second appears to be. It's being run as root with these options:

/usr/sbin/rtpengine --interface=xx.xx.xx.xx --listen-ng=7724 --timeout=60 --silent-timeout=3600 --pidfile=/var/run/rtpengine.pid --port-min=45000 --port-max=50000 --table=0

Running "netstat -lnp | grep 7724" does not report anything listening on port 7724 already.

Has anyone any ideas? Thanks in advance.