Yes, exactly. I’m following the guide here:
https://docs.docker.com/network/network-tutorial-overlay/ for standalone containers on different hosts. Everything is working fine until I try to ping one container from the other — or indeed try any form of network connectivity. Traffic is going back and forth correctly on ports 2377 and 7946 but tcpdump shows that neither host is initiating traffic on port 4789 (UDP). Firewalls are disabled on both hosts, so that’s not an issue. Networking is fundamentally working on both containers — that is they can see the internet and other containers.