Yep. corporate firewalls are tough to deal with.
You never know what they have instituted.
I deal with them all of the time.
Most times with no success.

But anyway for starters v7.5.3 has been patched with a security update which it appears you are not using.
So even if you upgrade right now. it will not correct prior hacking to your board, if that is the case.

Blue Man Group
There is no such thing as stupid questions. Just stupid answers