1) Network
- Switch networks (Wi‑Fi ↔ 4G/5G).
- Disable VPN/proxy.
2) Browser/app
- Private window.
- Clear cache/cookies.
- Update the app.
3) Account
- Confirm credentials.
- Sign out/in.
4) Payments
- Check limits.
- Try another method.
- If it persists, contact support.