We receive following error when launch <book>.ACSM file:
Connection Error Detected, Digital Editions could not connect to the fulfillment server. Please make sure you are connected to the internet. Our ISP is LondonGrid for Learning - will need details of URL/port etc - to submit unblock request. Please could you provide?
From quick experiments, for me it was 188.8.131.52:443 (no name for that ip address)
However, that IP address is owned by Akami, not Adobe, so I don't know how consistent that address would be.
At least I am UK, so it may use the same Akami route to Adobe as you need.
All I can suggest is to get that unblocked and see if it helps.