Startup Delay while IPv4-only VPN is active
Firefox configuration changes to fix startup delay if a IPv4-only VPN is active
Edit /etc/gai.conf and uncomment/adjust the line
precedence ::ffff:0:0/96 100
This increases the preference of IPv4-mapped addresses over IPv6.
Disable captive portal detection
In the web browser's about:config, set:
network.captive-portal-service.enabled → false network.connectivity-service.enabled → false
This removes startup probes that can hang on a misconfigured IPv4-only VPN.
— Martin Burnicki martin.burnicki@burnicki.net, last updated 2025-09-11