Browser slowdown if ipv6 DNS over HTTPS is configured without ipv6 connectivity


Description of the issue:
Pages take much longer than usual to load if ipv6 DNS over HTTPS is configured in Windows, without having ipv6 connectivity (no public ipv6 IP address).

How can this issue be reproduced?

  1. Go to Windows network settings.
  2. Setup DoH for both ipv4 and ipv6 (ControlD used for this test)
  3. Restart the browser and try to load youtube.com or reddit.com

Expected result:
When ipv6 lacks connectivity, the browser falls back to ipv4 quickly.

Brave Version( check About Brave):
1.70.126

Additional Information:
The issue does not affect Chrome or Edge, they seem to fall back to ipv4 much quicker.

Workaround:
In the Windows DoH settings, only enable and set the ipv4 DNS servers, not the ipv6 ones.
OR
Disable ipv6 in Windows for your network card.

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