Is your Phabricator running in AWS? Probably this information below could help you
Phabricator requires that you access using the specific configured domain. This domain is the public IP for all cloud options except AWS cloud. For this cloud you should use the domain like ec2-aaa-bbb-ccc-ddd.compute-1.amazonaws.com. If you access using the IP you will see the following message:
So in order to access to your phabricator instance in AWS you need to go through the domain http://ec2-aaa-bbb-ccc-ddd.compute-1.amazonaws.com . If you want access using the IP address you can add it on the phabricator settings running the following command, replacing IPADDRESS:
$ sudo /opt/bitnami/apps/phabricator/htdocs/bin/config set phabricator.allowed-uris '["http://IPADDRESS"]'