Do you also have a hardware firewall/router? Or are you plugged into the modem/phone line directly?
It's a possibility you might have your uPnP settings off. As long as you can get to the internet, you shouldn't have an issue with only 1 firewall on. But if you have 2 (Hardware and software) you might run into some unforeseen issues for secure ports.
I'm not sure what port the DRM works on, but my guess would be that it's either "https" or port 8080.
Are you running into this problem on any other websites?
