Check internet before the VPN
Disconnect the VPN and open an ordinary website. If it fails, fix Wi-Fi or mobile data first. Some public networks require signing in through a network portal before internet access is available.
Check time and permission
Make sure you have connection time available in the app. Accept Android's VPN permission when prompted. Close any other active VPN app before retrying.
Try another server
Start with Smart Connect. If it fails, choose another server in the same country or another country. Lower latency may help, but it does not prove a server can reach every website. If you need a particular IP country, check it after connecting or switching.
Connected but no internet?
Connected means the app reported a tunnel connection; open several sites to verify traffic actually passes. If all sites fail, try another server and then another network. If only one site fails, the problem may be that site or its restrictions.
When do TCP and UDP help?
TCP and UDP are ways to carry OpenVPN traffic. Networks may handle them differently, and the app uses connection options and alternatives based on available information. A protocol change does not guarantee bypassing a block, and latency is not a download-speed test.
Send a useful report
Update from Google Play. If the problem continues, use the report option in settings with the app version, network type, selected country, attempt time, and error message. Do not send passwords or private browsing content.