Found a solution:
Set env var HOST to 0.0.0.0, this is picked up by Strapi and then Strapi claims to listen on http://0.0.0.0.0:1337.
This is a bit strange, given the contents of config.server.js which should set 0.0.0.0as a default, but so be it.
Maye this is true for 4.14 only as my instances of 4.15 don’t need this fix, just guessing.