Cannot login to private docker registry
grrr... answering my own question....
so what happened was that i was using the systemctl drop-in's... and node B and the registry node were both in RFC1918 space... so in order to allow docker to download from the official docker registry, it was set to use:
[Service]Environment="HTTP_PROXY=http://<proxy>:3128/"which of course is rather restrictive and hence not forwarding the packets to my private registry.
removing this dropin under /etc/systemd/system/docker.service.d fixed the problem!