Please make sure your device is in a stable network environment. You can try to change the network environment (Wi-Fi/LTE) to get a more stable network environment.
If this still cannot solve your problem, can you please provide the following information:
1. Country and City: 
2. Time of Issue: 
3. IP when cannot connect (You can go to https://whatismyipaddress.com/ to check):
4. Screenshot of the error message