Login errors generally fall into a few clear categories, each with its own fix.
“Invalid username or password”
Re-check both fields for typos or extra spaces copied along with the text.
“Connection error” or “unable to connect to server”
Usually a network issue rather than a credentials issue — confirm your device is online, and double-check the server URL is complete.
“Subscription expired”
Your plan period has ended; renew to restore access — see the renewal guide.
“Max connections reached”
This means the subscription is already active on another device at the same time — each plan covers one simultaneous device.
Error persists after checking everything
Contact support with a screenshot of the exact error message.