|Maybe the logon in tied somehow to the user name?|
Could be some cache deal, start private session maybe.
You may have some sort of certificate that allows you to access the page.
It may be that some security setting differs.
Some sites allow you to contact by using new name. Not sure but It might be https://email@example.com or such.
Are you using a VPN to access work?
If it is for work then why not ask your IT people?
A Pit Bull is like a gun you can pet. And there is no safety on it.