redirects to hostname:port rather than -Dmingle.siteURL

Hi

We are running mingle 3.1 which is installed as service. I have configued the appropriate site URL where the mingle instance is accessible. But after loggin in it redirects to the server's hostname:port and I am not logged in. However navigating to siteURL I am logged in and all URLs are presented as expected. After "sign out" it again redicts to hostname:port.

I am not the one who installed and configured it in the first place and the one who did is not around. So my apologies if it is too trivial, but would appriciate if you could save me some time and direct me to the right config.

Thanks,

Abdul