The DevTest Portal seems to work fine except that after a couple of logins, not necessarily coming from the same user, there is no response after entering the correct credentials.
The only way to get the Portal working is rebooting DevTest services.
This is a known issue with DevTest on release 10.0.0.431.
This issue is fixed with DevTest 10.1.
There is patch with a fix for DevTest on release 10.0.
To get access to this fix, please open a support ticket and reference the case number DE269196.
You can open a support ticket via CA Support Online or call 1-800-225-5224.