Live View Not Working

Been sooo frustrated for about a month going back and forth from Ring support and internet provider, AT&T in trying to figure out why I can’t see live view. After trying everything from both sides and replacing router with no change, they’re now saying need to open up firewall and I want to refuse due to security risk. Why would this be the case? All devices were working fine for quite awhile and then all in one day all live views on one doorbell and 3 cameras stopped. Need advice on firewall issue.