IPv4 broken on GoogleFi LTE

afontenot says,

After installing the most recent update (via fdroid) I can’t access anything over IPv4 - so most websites. IPv6 routing works. Just for example, if I try to ping google.com in Termux, I see “no route to host”. When I try with ping6 it works.

I tried reverting to the previous version and the problem goes away. I’m using the DNS-only mode.

This issue is only when using cell data. WiFi is fine.

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This has also been known to happen with Google Fi / United States.

A couple things come to mind:

1. IPv4 routes aren’t being routed by Rethink even when there’s IPv4 connectivity (either through IPv4 in IPv6 or DS-Lite or DNS64/NAT64 or Teredo, etc)?
2. DNS endpoint does not respond to A records?

[ignoramous]

In v053k (F-Droid and Play Store flavours should show up by next week), we’ve now defaulted to IPv4-only mode. For us to fully support 464Xlat and yet not break HappyEyeballs, we would have to cleverly handle the ICMP protocol. This will likely happen in v054 (due Nov / Dec 2022).

[afontenot]

We are blocked by implementing a proper ICMP gateway before we can address this issue. Regardless, it is a priority item for us.

That’s good to know. I suspect quite a few users will run into this issue; this seems likely to be a dupe for instance: https://github.com/celzero/rethink-app/issues/558

You perhaps, iff you’re up for it, testing it out for us is one (the only?) way out (:

Sure, I can test stuff as necessary. I did manage to get a self-signed build working with Android Studio, so if necessary I can build and test proposed patches.