Not forwarding to docker containers

[trendmonkey]

Hi,

I have npm running in a docker container with 3 proxy hosts defined, DNS for all 3 points correctly to the docker host.
Each of the proxy hosts is set to http and to forward to the appropriate container and internal port - npm is on the same docker network as all the proxy hosts.

One (adminer) forwards with no issue at all.
One (portainer) gives no 404 but Firefox shows "we're having trouble finding that site" - however it is reachable directly on the mapped host port but not via npm on either the container port or the mapped host port.
One (Wordpress) show's the npm congratulations page (despite 404 page being selected in settings) - also reachable on the mapped host port but not via npm using host or container ports.

I've no idea what's going on so would really appreciate any insights. Cheers.

[trendmonkey]

Solved.
My provider firewall was blocking only permitting DNS on UDP not TCP.