Compare a single change at a time
Compare routes on the same device, network and task, and repeat the check instead of trusting a single speed figure. Distance, congestion and the destination service all play a part in what you feel.
Kuaimiao VPN
Smooth the next connection.
Keep comparisons simple: change one factor at a time, test the service you actually use and record the route and network when something fails.
Once the network changes
Once you move from Wi-Fi to mobile data or to a different hotspot, check that plain internet access still works. Reconnect and then read the status inside the app, because a stale connected icon proves nothing about the new path.
Make the issue reproducible
Note down the platform, the system and app version, the network type, the route, the exact error text and roughly when it happened. Say whether every site fails or just one - far more helpful than a screenshot that only claims the VPN is connected.