Sometimes Safari on iPhone (and iPad) refuses to display a new version of a web page. You might notice this particularly if you are a web programmer. It looks like changes which have been made don't exist. There is no simple command to force a reload, like there is on the desktop version of the app, so use this workaround:
Turn ON AirPlane mode. Turn OFF wifi. Refresh the page (it will fail; that's what we want). Turn AirPlane mode back off. Refresh the page to get the updated version.
This fixes a number of issues; it seems to fix Airdrop problems as well.