tinsukE

Oh, you’re right.

It seems to have been implemented and working on 138, but broken since 140 (my current version), with a fix scheduled to come on 142.

I’m looking forward to that one!

Oh, I meant mutual TLS by “it”. Edited.

That’s no bug, mTLS just isn’t implemented on Firefox (for Android) currently.

There are 2 proposed solutions on that thread:

1. It was possible on old versions of FF, but not the current ones. I believe this to be related to the versions prior to the revamp that happened circa 2020. (the author refers to a version that was already “old” by 2022). So it was something supported on OG Firefox, not not on the new (current, by 5 years already) version.
2. Using the debug menu’s secret settings to enable “Use third party CA certificates”. This is available on current FF, but that’s no mutual TLS. It is about allowing CA certificates that you installed yourself on your device for server TLS auth.

Tried it and it was a breeze to set it up with Caddy!

Problem was… lack of client side support, specially on mobile.

Many (most?) client apps don’t support it.

Use the PWA from your browser, you said? I hope you like Google and using Chrome, because Firefox for Android doesn’t support it (mTLS) 😭 (for now, see replies)