Gitlab container registry login trouble

Hi there,
I self-host Gitlab Ultimate for The University of Texas at San Antonio. It is currently at the latest version 13.8.something.
I want to start using the container registry for my DevOps class.
Following the container instructions for myproject on Gitlab, I execute:
docker login <my Gitlab host>:5050
and this returns:
Error response from daemon: Get https://<my Gitlab host>:5050/v2/: Service Unavailable

When I type:
docker login <my Gitlab host>
it returns:
Authenticating with existing credentials... Login Succeeded

but a docker push after that does not work. using port 5050 produces the error:
The push refers to repository [<my Gitlab host>:5050/docrob/myproject] Get https://<my Gitlab host>:5050/v2/: Service Unavailable

and a push without port 5050 produces a bunch of html, essentially saying:
error parsing HTTP 404 response body: invalid character '<' looking for beginning of value: ... more html to follow

I am using Apache to serve up the Gitlab server and I don’t see anything on the server listening to port 5050. Is there supposed to be a server process listening to that port? <my Gitlab host>:5050 is what is in my gitlab.rb config file for the registry URL.

Thank you for any help!