I have installed Portal 10.3.1 along with Server and ArcGis Desktop.
Web adapter has been configured - at least to the best of my current ability.
I can access the Portal page both using port 7443 and port 80 via the Web adapter, I believe.
I can browse maps, and start a log-in, but after submitting the correct user-id and password, the portal keeps displaying the log-in page (without the actual fields for ID/PW). I can still access menu items in portal.
I believe I have added all the required hostnames to the 'secure sites' in IE.
Submitting a wrong password does give an error message, so the portal admin account has been created and can be accessed.
Any ideas on how to proceed ?