1. Press the green button in files - have you copied the address exactly as it says there. Faq says that John's Iphone is Johns-Iphone, but it actually is John-s-Iphone - so double check!
Still no connection?
2. Select your iPhone in iTunes, click on it again so the name becomes editable (like with a file in Finder), and type a new name. RunFiles and see what Bonjour URL it gives you. Try to connect with it. Rechange your name back - try with the new name as Bonjour shows it.
Still no connection?
3. Open Files on your phone and open a cmd window in windows
Type dns-sd -B _http._tcp -check the name it gives you at the end - in my case it says ****-s-iPhone
Type dns-sd -L "Name you got from the command you executed before"_http._tcp
Use the name that comes up after this command within your bonjour connection.