What does your Apache configuration look like? It sounds like Apache isn’t configured to route requests through the GitLab-workhorse component right now.
Take a look at the example Apache configuration in the GitLab Recipes project for more information
FINALLY!! The answer was gitlab-workhorse – setting it in the Apache gitlab.conf file to listen on port 8181 instead of port 8080. It only took 3 days to find this.