Happyeyeballs is not fully supported by some softwares

[mzz2017]

What would you like us to improve

If local has ipv6 addresses and routes and remote proxy doesn't, eBPF program will disable the ipv6 traffic to this remote proxy.

However, some softwares have bad happy eyeballs support and always retry.

Node.js

Occurs since v17.
Fixed in v20.

nodejs/node#41625
nodejs/node#44731

Powershell

Occurs on but not only v7.3.4.

wget

No version context was given.

Wait 60s for timeout and fallback.

What should do

We should disable dropping ipv6 traffic if node has no ipv6 connectivity (at least) in domain++ mode.

Or, only drop them in IP mode (not a good idea if no sniffed domain).

[dae-prow]

Thanks for opening this issue!

[MarksonHon]

Nushell might have same problem

[mzz2017]

These bugs are really headache; these apps set high priority for ipv6 and not support happy eyeballs at the same time!

[mzz2017]

Maybe a better solution is to enable ipversion_prefer: 4.
#136 should be given a higher priority.