I face issues while testing localhost URLs or private servers in Safari on macOS/OS X and iOS.

Safari, both on Desktop (OS X, macOS) and on real iOS devices has known issues with resolving URLs which have the string "localhost". We recommend you try the following:
  1. Try replacing 'localhost' in the URL you are using with the IP address of the machine. For example, if you are testing the URL "http://localhost:8080/index.html" try using "http://<machine_ip_address>:8080/index.html" instead.
  2. Make sure you are using one of the supported ports to test the URL. The list of all supported ports can be found here.
In case the above two steps do not resolve your issue, please reach out to us at support@browserstack.com.