Please try connecting to another network and check if it’s working normally on your end. If it does, then there might be something blocking D5 Render in your previous internet. If you’re on a company setup, it might be best to consult your IT Department if there are any blocks (Antivirus or Firewall) on your end.
Can you send us a screenshot of the error prompt? Were you able to use D5 Render before, or is this your first time? And may I know the following details:
Email Address
Region
Internet Service Provider
If this issue just occurred, may I know if this occurred after an update or such?
You may also want to try using a VPN if there are any differences.