Windows ODBC connection trouble? ISP issue?

I have set up a pg database server for my organization on a cloud server
using PG 8.2;

I am trying to provide connections to the db for some members using MS
Access. I developed a small MS Access application using Windows ODBC - it
works fine from my house.

I have this line in pg_hba.conf:

Host all mydbuserID 0.0.0.0/0 password

BUT. I cannot re-create the ODBC connection in our organization's offices!

I have de-bugged by taking my laptop to the office - it will not connect to
the db there - but is ok at my house.
(I have also checked 2 other locations with public wi-fi; could not connect
from either of them)

This seems to be related to the ISP blocking data - I have ruled out the
router in the office.

Is this a common SNAFU to encounter?

I spent an hour on the phone with tech support for the office's ISP; the
guy insisted it could not be a problem on their side!

Is there something I could be overlooking?

Any help or guidance would be greatly appreciated.

Regards,

JPD