If you are running bare metal servers in the cloud provider OVH, you will likely run into communications issues with Docker’s overlay networking. In particular, overlay networking uses UDP port 4789 by default which conflicts with OVH’s internal use of VXLAN.
To resolve this, you can change the data path port for your Docker Swarm setup to a different value (for example, 9789 )
docker swarm init --data-path-port=9789