It means that you have some authorization issue or possibly some problem with cookies. Are you sure you are using official release without any modifications to the config?
Yes,installed two days ago on a clean debian 9
Well, made the typical changes to the config: email server and sales. Nothing else
Not sure what the problem is then. Are you sure there is nothing else that can affect it (e.g. proxy)?
Used the reverse proxy as seen in documentation
Then the problem is most likely with your proxy.
i found something weird. If you use the fqdn with the default port (no the proxy i provided before) it redirects automatically to https.
Tried putting in the address bar the ip and the port and it works like a charm.
Maybe apache web server is intercepting requests and making redirection to https?
i'll keep investigating
Edit: Solver. Typo error on apache configuration
It happens instantly.
You can try by yourself in my server