I set this up on my instance about a week ago and it works perfectly, thank you!

LastPass Authenticator can use SHA256, it works for logging in to my Lemmy instance. And you can use the app independently of LastPass, keeping everything on your device.

I believe the issue is that Lemmy expects the codes to be generated using the SHA256 algorithm, while most generator apps use SHA1.

I don’t know how it works under the hood, but it makes sense to me from the perspective of an instance admin: the modding decisions I make on my instance should carry over to the federated copies of my instance’s communities, and vice versa.

The app will show a pop up to sign up to preload his app “Sync for Lemmy”, not to sign up to an account on a Lemmy instance.

I see, thank you for the insight. According to this comment, after an instance on 0.18.0 is running one can still set it to private with federation enabled, so it seems this check is only preventing the instance from starting in that state.

I guess this comment was originally a response to a different problem, but in my case it wasn’t a “hack” - there was no problem with enabling federation on a private instance, and it worked as expected. I thought of a “private instance” as “can’t see it unless you log in, but federates exactly like a public instance would”, and that’s exactly how it worked in 0.17.4, but I understand if, in principle, it wasn’t supposed to work like that. Again, there was no need to hack anything on my end, it just worked.

At least on 0.17.4, with Private Instance and Federation enabled, the comments and posts I made to remote communities were federated correctly to other instances. The change seems very intentional, as shown by the error message I got after I upgraded:

lemmy_1 | Error: LemmyError { message: Some("Cannot have both private instance and federation enabled."), inner: Cannot have both private instance and federation enabled., context: SpanTrace [] }

ncgnzlcl_lemmy_1 exited with code 1

Thankfully the error was very explicit:

lemmy_1 | Error: LemmyError { message: Some("Cannot have both private instance and federation enabled."), inner: Cannot have both private instance and federation enabled., context: SpanTrace [] }

ncgnzlcl_lemmy_1 exited with code 1

With both options enabled, my instance operated as expected on 0.17.4: there was no anonymous access to anything, but once logged in you could subscribe to communities from any public instances. They don’t seem incompatible at all, and my posts and comments were federated correctly outside of my instance.