Since early afternoon yesterday, it appears Comcast is blocking access to our server Supercell. It took us until now to recognize the larger trend as it just started out as a report from a couple of customers that we were trying to troubleshoot individually. Since then more reports have arrived.
I just spoke to Comcast and the technician was able to confirm that he too was unable to trace to this server and it was stopping within their network. He escalated a ticket to network engineering. He will be calling me back when they respond however he said that's managed by another company and he didn't expect we'd hear back today. They had no way for me to escalate this further.
I will update this thread as soon as I know more.