docker run -p 9991:9987/udp -p 10081:10080 -p 30031:30031 -e TS3SERVER_LICENSE=accept -e TS3SERVER_FILETRANSFER_PORT=30031 -e TS3SERVER_QUERY_PROTOCOLS=raw,http --name ts1 teamspeak
/var/run/ts3server/ts3server.ini
docker run -p 9991:9987/udp -p 10081:10080 -p 30031:30031 -e TS3SERVER_LICENSE=accept -e TS3SERVER_FILETRANSFER_PORT=30031 -e TS3SERVER_QUERY_PROTOCOLS=raw,http --name ts1 teamspeak
/var/run/ts3server/ts3server.ini
Believe it or not, this is the expected behavior. You need to explicitly specify the filetransfer ip to be able to set the filetransfer port.