iOS 10: Safari cannot open the page. The error was: "Not allowed to use restricted network port" I'm having an issue with iOS 10.0.1 and Safari 10. In iOS 9 and Safari 9, I am able to go a web site on port 4190. As soon as I use an iOS 10 device, I get this error message using Safari 10:

Safari cannot open the page.
The error was: "Not allowed to use restricted network port".

I read online that some ports are blacklisted. Best I could find is a KURL.cpp blockedPortList, but I don't see port 4190 blocked. 

I see the error message is in this piece of code:
#define WebKitErrorDescriptionCannotUseRestrictedPort UI_STRING_INTERNAL("Not allowed to use restricted network port", "WebKitErrorCannotUseRestrictedPort description")

Any ideas?
The reason the port is blocked is because Apple considers it is a port that is open to trojans and viruses, so it automatically blocks those ports. it has to do with the release of Xcode(how mac programs are designed and written)
App Transport Security
iOS 9 introduces a new security feature that blocks non-HTTPS traffic in your app. However, this is a new feature that is only enabled for apps building with XCode 7 and iOS 9 SDK today. It will not break existing apps.
Since the changes above require recompilation, this will impact your development process and manifest itself as a breaking change.
To fix, edit the MyApp-Info.plist file and add the contents of this patch.
UPDATE: In short, the port was closed by Apple due to viruses. It worked on the older versions of Safari because the app was made on an older version of the program to used to create it (Xcode). So basically by updating, you installed a version of Safari that will not open those ports blocked by Apple.