Why VPN connections fail on difficult networks
A practical checklist for protocol blocking, DNS trouble, packet loss, and network switching.
Start with the network
Test the same connection on Wi-Fi and mobile data. If only one fails, the problem is likely the network path rather than the device.
Check the failure stage
Separate app startup, server-list loading, tunnel negotiation, DNS, and site-specific failures. They have different causes.
Avoid endless retries
Reconnect once, change network once, and record the exact time and error. Repeated retries can hide the original signal.