In a firewalled or otherwise air-gapped DTR installation, sometimes the Settings page may be inaccessible due to the upgrade-check function being unable to reach the Internet to check for an available update.
This may result in the DTR Settings page load icon spinning indefinitely.
dtr reconfigure, set up a bogus HTTP proxy that points to itself:
docker run -it docker/dtr reconfigure --http-proxy 127.0.0.1 --ucp-insecure-tls
Provide your UCP external URL, admin username, and password at the prompt. Wait for DTR to reconfigure, then check the Settings page again.
You should be able to access the Settings page now.
In the event you should need to remove the HTTP proxy setting, it can be removed by setting the value of
--http-proxy to an empty string, like so:
docker run -it docker/dtr reconfigure --http-proxy '' --ucp-insecure-tls