The answer to this question will be very different in Iran and countries that have Internet filtering. In Iran, people just want to have a VPN that is easy to download from Epistor, and other things like watching YouTube videos and, more recently, making it easier for them to access Telegram.
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But the right to choose for the iPhone has been greatly diminished by Apple's updates, as well as the new filtering system that creates widespread disruption to VPN connectivity.
Because some VPN services on the iPhone, such as openvpn, are often not properly usable, especially openvpn UDP, most packets are dropped by filtering.