No networking for stacks

Hi folks,

I’ve rebuilt my Debian box - simple & vanilla (done this a few times now) - followed the RTFM, but when I try to stand up a simple stack, I cannot get networking to function connectly.
example: https://pastebin.com/BQrstZFw

this is doing my head in!

I can get access to the instance if I use docker compose to stand up the “stack”, but not swarm/stack/services.
logs all check out & depending on the network selected, I can curl is from localhost/server, but not from LAN.

I don’t think it’s server-level networking, as the containers are reachable when stood up as standalone or via compose, but not via service/stack.
This would seem to indicate it could have something to do with the networking within swarm, but I cannot figure out how to debug - or if it’s a bug I need to file.

I’ve dutifully followed the documentation (several times), expecting to have a functional server stack I can use by the end, but this is simply not the case.

What have I missed?
I’m sure it must be something trivially small, but for the life of me I cannot figure out what & where.

Any help would be greatly appreciated.

Same problem, same solution…