credentials to proxy software don't work in Sandbox

Moving .exe file into box:


Software opens as expected,  Username/PW prefilled and correct. But getting "login failed" message:


Per 911, when this happens it's usually a network/internet issue.

However, everything else works within Sandbox without problems.

I know the software is being used, so should work.

Any hints as to what needs to be changed in configuration to fix the login issue?