service logs of worker indicate Could not resolve hostname mpi-master or Connection refused

[13ean]

I have created service

when inspect logs of worker, get infomation like this

[simonholgate]

Out of curiosity, what cloud provider are you using?

I had a real problem connecting to the containers on Google Cloud because the docker encryption on the subnet isn't supported by the NAT. I believe this is the case on AWS too:
moby/moby#37115

This isn't an issue on Digital Ocean though.

My solution was to remove the --opt encrypted line from swarm.sh

Another possible issue is that the firewall hasn't got all the necessary ports open.