Copilot GitHub Connection Error from Toad for Oracle Subscription – "FetchError: Client network socket disconnected before secure TLS connection" (4380809)

When connecting to GitHub Copilot via Toad for Oracle Subscription, the client fails with the following error:

Status: FetchError: Client network socket disconnected before secure TLS connection

The connection attempt does not reach the TLS handshake stage, preventing the client from authenticating or communicating with Copilot servers.

This issue is typically caused by network or system configuration blocking or interrupting the connection, such as:

• Firewall or corporate network restrictions preventing outbound HTTPS traffic to GitHub or Copilot endpoints.
• Proxy servers or VPNs are improperly configured or dropping TLS connections.
• Antivirus or endpoint security tools are interfering with TLS traffic.
• Local network instability or connection drops.
• Outdated Node.js, VS Code, Toad for Oracle Subscription, or Copilot extension versions affecting TLS support.

1. Verify Network Connectivity:

   • Ensure outbound HTTPS (port 443) access is allowed to:
     • github.com
     • api.githubcopilot.com

2. Check Proxy / VPN Settings in Toad for Oracle:

   • Open Toad for Oracle → View → Toad Options → Online and AI → Proxy Settings.
   • Verify:
     • Proxy type (HTTP or SOCKS) is correct.
     • Proxy server and port are correctly entered.
     • If authentication is required, provide username and password.
   • Enable Use system proxy settings if your network requires it.
   • Use any available Test Connection option to verify the proxy configuration.

3. Disable VPN:

   • Temporarily disconnect from any VPN and test the GitHub Copilot feature in Toad for Oracle Subscription.
   • Some VPNs may block or interfere with the TLS connection.

4. Inspect Security Tools:

   • Temporarily disable SSL/TLS inspection or endpoint security tools to confirm they aren’t blocking the connection.

5. Test Connectivity Outside Toad (Windows):

   • Open PowerShell and run:
      

     Test-NetConnection github.com -Port 443
   • Ensure the TcpTestSucceeded result is True.
   • This confirms basic network connectivity to GitHub over port 443.

6. Update Software:

   • Ensure Node.js, VS Code, Toad for Oracle Subscription, and the GitHub Copilot extension are up to date to avoid TLS compatibility issues.

7. Alternative Network:

   • If the issue persists, attempt a connection from a different network (e.g., home or mobile hotspot) to isolate corporate network issues.

8. Add a Trusted Certificate in Toad

   1. Open Toad and go to View → Toad Options.
   2. In the bottom-left corner of the Options window, use the Find search box.
   3. Type Online and AI, then double‑click the Online and AI section in the results.
   4. In the GitHub Copilot section, you will find an option to add additional trusted certificates.
      Use this area to include your internal certificate.

References / Additional Notes:

• This is a network-level connectivity issue, not a Copilot or GitHub bug, when using Toad for Oracle Subscription.
• Work with IT/network teams to allow necessary access for Copilot functionality in Toad for Oracle.