[IPv6] ampinstmgr prefers IPv4 over IPv6 failing to download core archive

[BroOtti]

Operating System

Debian 12

AMP Version and Build Date

AMP Instance Manager v2.6.2 built 17/06/2025 09:12

AMP Release Stream

Mainline

I confirm that

• [x] I have searched for an existing bug report for this issue.
• [x] I am using the latest available version of AMP.
• [x] my operating system is up-to-date.

Intended Action

First time install on an IPv6-only server with NAT64+DNS64.

Expected Behaviour

ampinstmgr should be able to pull the core archive from cdn-downloads.c7rs.com Especially as cdn-downloads.c7rs.com does have an AAAA entry.

Actual Behaviour

ampinstmgr fails to download the core archive because Network is unreachable. Downloading the archive with wget does work, as it's reachable just fine over native IPv6 without the need of NAT64. ampinstmgr seems to force IPv4 though it could just use IPv6 fine.

Reproduction

1. Setup an IPv6-only server with NAT64+DNS64 (So, that getamp.sh and auth.cubecoders.com works as they miss AAAA entries; Also GitHub sucks on IPv6)
2. Follow the basic installation instructions and see it failing on the createDefaultInstance step.

[BroOtti]

Working workaround is to configure the DNS64 to remove A entries from answer

[PhonicUK]

The reason for this is due to the high number of setups where IPv4 works, IPv6 doesn't but IPv6 gets preferred. IPv4 should be treated as a requirement at this time using 4in6 or similar.

[kdallas]

@PhonicUK -- is it possible for this to get any attention please? An increasing number of us are using hosts that are allocated IPv6 out of the box. When making an HTTP request to https://cdn-downloads.c7rs.com all we'd expect is that the response can come back over the same protocol on which it was initiated. (Without having to disable IPv6 or other funky routing workarounds).

Evidently you have the AAAA DNS records set through Cloudflare already so this shouldn't be a big ask.

[BroOtti]

@PhonicUK -- is it possible for this to get any attention please? An increasing number of us are using hosts that are allocated IPv6 out of the box. When making an HTTP request to https://cdn-downloads.c7rs.com all we'd expect is that the response can come back over the same protocol on which it was initiated. (Without having to disable IPv6 or other funky routing workarounds).

Evidently you have the AAAA DNS records set through Cloudflare already so this shouldn't be a big ask.

As already mentioned on Discord, your problem isn't related to this issue.

[BroOtti]

The reason for this is due to the high number of setups where IPv4 works, IPv6 doesn't but IPv6 gets preferred. IPv4 should be treated as a requirement at this time using 4in6 or similar.

Would it be possible to implement a function for AMP to try first IPv6 and if it fails it tries forcing IPv4? Maybe also alerting the user about the broken IPv6 connection. IPv4 shouldn't be treated as a requirement. IPv6 is the standard for 8 years already and exists over 20 years. We should focus more on IPv6. I know there are still games without IPv6 support, but that shouldn't force AMP to have IPv4 as a requirement.