okay, step by step...
open the port 3478 for tcp/udp of your router .
create a folder for the turnserver.conf
mybe like this /srv/dev-by-label-HDD/dockerapps/turnserver/
gernerate a secreat code: openssl rand -hex 32
create and put in the folder the turnserver.conf like this
Then i have used Portainer:
use the docker image from instrumentisto/coturn
port configuration: 3478:3478tcp and 3478:3478udp
volume setting:
Host Volume:
/srv/dev-by-label-HDD/dockerapps/turnserver/turnserver.conf
Path in container:
/etc/coturn/turnserver.conf
Network:
I use the same network like my nextcloud container is running
Then pull the container image with this options and edit the options in nextcloud talk