Consider using the default RendezVous / Mailbox servers for easier interoperability, and ensuring they work

[nekohayo]

To Reproduce
Steps to reproduce the behavior:

1. Install Destiny on a smartphone (from the F-Droid repositories, in my case)
2. Install Warp on a desktop
3. Try to throw files from one to another with the default out-of-the-box configs

Result

The file transfers fail, and it is not obvious why or how to fix the issue, and it will be painful to fix for each person/device you encounter.

Warp uses the default servers whereas Destiny uses its own "LeastAuthority" rendez-vous servers (which is presumably why it forces you to accept a user agreement on startup… why should that be the case?).

Both Destiny and Warp are configurable since #239, however this makes for a bad user experience (especially with non-technical users) because you have to somehow:

1. know that the servers mismatch is the problem
2. know what to put on both sides
3. type it all by hand (or fingers!) in the configuration GUIs.

…and even then, you can screw it up. For example, I configured Warp like this to try to match Destiny, for testing:

…and it worked one time for me, then in subsequent tries it stopped working because... I'm not sure why:

It never worked again, even if I restart both apps.

Then I tried configuring Destiny to use the same default servers as Warp (those you can see in the descriptive label text in the screenshot above), but whenever I try to send a file with Destiny, it gives me the "Oops..." error message:

Unfortunately, Destiny cannot connect to the Least Authority servers

(even though it's not configured for the Least Authority servers, but the magic-wormhole.io servers).

So no matter what I do, it doesn't work, at least not consistently. Overall, this situation makes for a painful default UX.

Expected behavior

It should work out of the box, to make it easier for non-technical users to adopt this technology. If the user is James Bond and needs to run their own servers, then they already are technical enough to set up servers on every client, but it should "just work" for everybody else.

Could Destiny use the same default servers as Warp (and skip the server user agreement), and ensure those work out of the box?

Maybe the Least Authority and Magic Wormhole servers could be provided as multiple default choices too, if the user wants to switch from the M-W to L-A servers.

Additional info

This was tested with all devices connected to the same WiFi connection. This connection supports IPv6.

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App Version: 1.0.3

Smartphone (please complete the following information):

• Device: Android
• OS Version: LineageOS 16 (Android 9) with FDroid