When a connection breaks

The bot is kicked or leaves the voice channel

If someone kicks the bot, disconnects it, or the bot is removed from the server, Nyra closes that guild's player on the server and drops the GuildConnection. No event is raised for this.

After that, nyra.GetConnection(guildId) returns null, and connection.IsConnected is false. Joining again gives you a new GuildConnection, so subscribe to its events again.

The bot is moved

Nothing breaks. The connection stays, and connection.ChannelId changes to the new channel.

The server drops

Nyra reconnects by itself, waiting longer after each failure. It never stops unless you set MaxReconnectAttempts in NodeOptions.

With Resuming = true, the server keeps the players for ResumeTimeout, and audio continues when the node is back. NodeReady tells you what happened:

nyra.NodeReady += (sender, args) =>
{
    Console.WriteLine(args.Resumed == true ? "Session resumed" : "New session");
    return Task.CompletedTask;
};

After a resume, await connection.RefreshAsync() updates a connection with what the server says. await node.ListPlayersAsync() lists every player of the session, including guilds this bot isn't connected to.

The players are gone

If the session can't be resumed, or a NodeLink worker crashes, the players are lost. Each affected connection raises GuildConnectionInvalidated. args.LastChannelId is the channel it was in, so you can rejoin:

connection.GuildConnectionInvalidated += async (sender, args) =>
{
    if (args.LastChannelId is not { } channelId || nyra.GetNode() is not { } node)
        return;

    var fresh = await node.ConnectAsync(args.GuildId, channelId);
    // fresh is a new connection, subscribe to its events here
};

The node gives up

When MaxReconnectAttempts runs out, or the first connect fails for good, NodeDisconnected is raised with Final = true, and the node stops trying. args.Exception has the last error.

nyra.NodeDisconnected += (sender, args) =>
{
    if (args.Final)
        Console.WriteLine($"{((Node)sender!).Name} gave up: {args.Exception?.Message}");
    return Task.CompletedTask;
};

Guild connections on that node stay registered until it connects again. Call ConnectAllNodesAsync() to try again.

More info

Other events that help when something goes wrong are nyra.NodeError, nyra.NodeWorkerFailed, connection.WebSocketClosed and connection.HandlerError, and on NodeLink PlayerReconnecting, PlayerConnected, PlayerCreated and PlayerDestroyed. What each one means is on GuildConnection and NyraExtension.