Fix Chrome ERR_TUNNEL_CONNECTION_FAILED on Windows 10 - MsMpEng.exe High CPU Fix Guide-How to Resolve Connection Refused on Port 80 in CMD

Updated 2026-06-14 05:46:00security-tools
Fix Chrome ERR_TUNNEL_CONNECTION_FAILED on Windows 10 - MsMpEng.exe High CPU Fix Guide-How to Resolve Connection Refused on Port 80 in CMD
Before changing system settings, save your work and note the exact error text so you can compare results after each step.

Extra verification checklist

  • Restart the affected app after changing permissions or configuration files.
  • Test the same workflow in a clean browser profile or a temporary user account.
  • Compare the result on another network if the error may be connection related.