I'm using IPv4 as well as IPv6 addresses in my home network. But Firefox uses always the IPv4 connection when I open a website. When I open the same website in MS Ed… (read more)
I'm using IPv4 as well as IPv6 addresses in my home network. But Firefox uses always the IPv4 connection when I open a website. When I open the same website in MS Edge, the IPv6 connection is used.
I've captured the network traffic during opening a website in Firefox, which is reachable over IPv4 and IPv6.
First I see two DNS queries (A and AAAA) for the domain name. Both responses containing the correct IP address, and they arrive nearly at the same time at the client.
Next I can see the TCP handshake. But it's send between the IPv4 address only. No IPv6 connection was attempted.
When I run the IPv6 test at https://test-ipv6.com, the IPv6 resuls are nearly fine. Only the web browser test says "Your browser has real working IPv6 address - but is avoiding using it."
When I run the same test in MS Edge, all tests are fine.
So it seems that this is not a OS or network issue. It affects Firefox only.
What I've already tried:
- Disabled all extensions
- Created a new profile
- Used the IPv6 address of the website instead of the FQDN -> Works fine.
- Checked DNS cache of Firefox (about:networking). It contains the IPv4 and IPv6 addresses of the requested websites
I guess that Firefox prefers the A record for some reason. But I've no idea why. Has anybody an idea what could causing this?