Can't authenticate via AD in IE from remote network (2.0.11.1080)

If I attempt to sign in from IE11 using a machine that is not logged onto the network, (but connected via VPN), the process fails, saying:

There was a problem with your request.

Please provide a username.

Please provide a password.

This works fine on the network, or remotely using any other browser.

Interesting - thanks for the heads-up, any other clues? (JavaScript errors etc?)

We don’t use IE’s integrated security, so the location of the browser/network configuration shouldn’t matter.

Are you accessing Octopus via HTTP or HTTPS, and do you use a custom port or VDIR?

Thanks!
Nick

No JS errors - the AJAX call to /api/users/login has an empty request body and returns a 400 HTTP error. Plain HTTP on port 80, running at root.

Further testing seems to suggest this is exclusively an IE11 problem. I can login with all older versions I have available on this machine and the working instances I tried on other machines are running IE10.