When I started the client from the system tray, the browser tried to open an URL like http://127.0.0.1:8200/signin.html?token=xyz (with xyz being the much longer token).
The browser did not show the client, but a login page “JWT signin token” and an input box asking for that token. Whatever I entered, I afterwards got an error page like (German version here):
Anscheinend gibt es ein Problem mit dieser Website
http://127.0.0.1:8200/signin.html?token=xyz hat einen Fehler zurückgeschickt.
Fehlercode: 404 Not Found
Vergewissern Sie sich, dass Sie die Adresse der Website richtig eingegeben haben.
The cause for this behaviour was just a Javascript blocker (Noscript plugin), which needed to trust 127.0.0.1:8200.
Maybe some informational hint would be possible, FAQ or the typical “you need to enable Javascript to use this page”.
Thank you.