Prefer IPv4 over IPv6

Operating Systems

• Linux: gai.conf
• Windows:
  • Modify registry key DisabledComponents under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters
  • OR
  • Modify prefixpolicies to prefer IPv4-mapped IPv6 address, see netsh interface ipv6 show prefixpolicies for current list
• macOS: N/A

Browsers

• Firefox: about:config → network.dns.disableIPv6 (disables IPv6, which makes IPv6-only sites inaccessible)

References

• https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/configure-ipv6-in-windows