ERR_TUNNEL_CONNECTION_FAILED, may occur when Chrome is unable to render the proxy response for some sites. Follow to troubleshoot your problem:

Try these fixes:

  1. Change your network settings
  2. Resetting your TCP/IP and flush your DNS

Fix 1: Change your network settings

1) Open your Chrome.  Then click on the More Options menu and choose Settings.

2) Click Show advanced settings…

3) Choose Change proxy settings under Network dialog.

4) Click LAN settings under Connections pane. Then uncheck use a proxy server for your LAN. Click OK.

5) Restart your PC to make change take effect.

Fix 2: Resetting your TCP/IP and flush your DNS

1) Run Command Prompt as administrator.
How to:
1-1) Find and right-click on Command Prompt from the Start menu.
1-2) Then choose Run as administrator.
1-3) Click YES when prompted by User Account Control.

2) Type the following commands  and press Enter after each.

ipconfig /flushdns 
nbtstat –r 
netsh int ip reset
netsh winsock reset 

3)  Restart your PC to make the change take effect.

Sorgente: ERR_TUNNEL_CONNECTION_FAILED error in Chrome [Solved] – Driver Easy