Try adding is lobby public

If lobby is public it will allow it to be recived as public lobby for joining it via some kind of automatic system...

client/ws_webrtc_client.gd

@@ -1,6 +1,6 @@
 extends Node
 
-enum Message {JOIN, ID, PEER_CONNECT, PEER_DISCONNECT, OFFER, ANSWER, CANDIDATE, SEAL}
+enum Message {JOIN, ID, PEER_CONNECT, PEER_DISCONNECT, OFFER, ANSWER, CANDIDATE, SEAL, GET_PUBLIC}
 
 @export var autojoin := true
 @export var lobby := "" # Will create a new lobby if empty.
@@ -20,6 +20,8 @@ signal answer_received(id, answer)
 signal candidate_received(id, mid, index, sdp)
 signal lobby_sealed()
 
+signal public_lobbies_recived(id, list)
+
 
 func connect_to_url(url):
 	close()
@@ -88,13 +90,15 @@ func _parse_msg():
 		if not candidate[1].is_valid_int():
 			return false
 		candidate_received.emit(src_id, candidate[0], candidate[1].to_int(), candidate[2])
+	elif type == Message.GET_PUBLIC:
+		public_lobbies_recived.emit(src_id, JSON.parse_string(msg.data))
 	else:
 		return false
 	return true # Parsed
 
 
-func join_lobby(lobby: String, single_host:=false):
-	var data = {"lobby":lobby,"single_host":single_host}
+func join_lobby(lobby: String, single_host:=false, public:=false):
+	var data = {"lobby":lobby,"single_host":single_host,"public":public}
 	return _send_msg(Message.JOIN, 0 if mesh else 1, JSON.stringify(data))
 
 
@@ -114,6 +118,10 @@ func send_answer(id, answer) -> int:
 	return _send_msg(Message.ANSWER, id, answer)
 
 
+func ask_for_public_lobbies(id) -> int:
+	return _send_msg(Message.GET_PUBLIC, id, "")
+
+
 func _send_msg(type: int, id: int, data:="") -> int:
 	return ws.send_text(JSON.stringify({
 		"type": type,

server/ws_webrtc_server.gd

@@ -1,6 +1,6 @@
 extends Node
 
-enum Message {JOIN, ID, PEER_CONNECT, PEER_DISCONNECT, OFFER, ANSWER, CANDIDATE, SEAL}
+enum Message {JOIN, ID, PEER_CONNECT, PEER_DISCONNECT, OFFER, ANSWER, CANDIDATE, SEAL, GET_PUBLIC}
 
 const TIMEOUT = 1000 # Unresponsive clients times out after 1 sec
 const SEAL_TIME = 10000 # A sealed room will be closed after this time
@@ -45,11 +45,13 @@ class Lobby extends RefCounted:
 	var time = 0
 	var mesh := true
 	var single_host := false
+	var public := false
 
-	func _init(host_id: int, use_mesh: bool, is_single_host: bool):
+	func _init(host_id: int, use_mesh: bool, is_single_host: bool, is_public:bool):
 		host = host_id
 		mesh = use_mesh
 		single_host = is_single_host
+		public=is_public
 
 	func join(peer: Peer) -> bool:
 		if sealed: return false
@@ -168,11 +170,11 @@ func poll():
 		peers.erase(id)
 
 
-func _join_lobby(peer: Peer, lobby: String, mesh: bool, single_host:bool) -> bool:
+func _join_lobby(peer: Peer, lobby: String, mesh: bool, single_host:bool, public:bool) -> bool:
 	if lobby == "":
 		for _i in range(0, 32):
 			lobby += char(_alfnum[rand.randi_range(0, ALFNUM.length()-1)])
-		lobbies[lobby] = Lobby.new(peer.id, mesh, single_host)
+		lobbies[lobby] = Lobby.new(peer.id, mesh, single_host, public)
 	elif not lobbies.has(lobby):
 		return false
 	lobbies[lobby].join(peer)
@@ -202,7 +204,7 @@ func _parse_msg(peer: Peer) -> bool:
 		if peer.lobby: # Peer must not have joined a lobby already!
 			return false
 		var dt = JSON.parse_string(msg.data)
-		return _join_lobby(peer, dt.lobby, msg.id == 0, dt.single_host)
+		return _join_lobby(peer, dt.lobby, msg.id == 0, dt.single_host, dt.public)
 
 	if not lobbies.has(peer.lobby): # Lobby not found?
 		return false
@@ -213,6 +215,14 @@ func _parse_msg(peer: Peer) -> bool:
 		# Client is sealing the room
 		return lobby.seal(peer.id)
 
+	if msg.type == Message.GET_PUBLIC:
+		var pb = []
+		for lb in lobbies.keys():
+			if lobbies[lb].public:
+				pb.append(lb)
+		peers[peer.id].send(msg.type, 0, JSON.stringify(pb))
+		return true
+
 	var dest_id: int = msg.id
 	if dest_id == MultiplayerPeer.TARGET_PEER_SERVER:
 		dest_id = lobby.host

server_node/server.js

@@ -35,6 +35,7 @@ const CMD = {
 	ANSWER: 5, // eslint-disable-line sort-keys
 	CANDIDATE: 6, // eslint-disable-line sort-keys
 	SEAL: 7, // eslint-disable-line sort-keys
+	GET_PUBLIC: 8, // eslint-disable-line sort-keys
 };
 
 function randomInt(low, high) {
@@ -85,11 +86,12 @@ class Peer {
 }
 
 class Lobby {
-	constructor(name, host, mesh, single_host) {
+	constructor(name, host, mesh, single_host, public) {
 		this.name = name;
 		this.host = host;
 		this.mesh = mesh;
 		this.single_host = single_host;
+		this.public = public;
 		this.peers = [];
 		this.sealed = false;
 		this.closeTimer = -1;
@@ -158,7 +160,7 @@ class Lobby {
 const lobbies = new Map();
 let peersCount = 0;
 
-function joinLobby(peer, pLobby, mesh, single_host) {
+function joinLobby(peer, pLobby, mesh, single_host, public) {
 	let lobbyName = pLobby;
 	if (lobbyName === '') {
 		if (lobbies.size >= MAX_LOBBIES) {
@@ -169,7 +171,7 @@ function joinLobby(peer, pLobby, mesh, single_host) {
 			throw new ProtoError(4000, STR_ALREADY_IN_LOBBY);
 		}
 		lobbyName = randomSecret();
-		lobbies.set(lobbyName, new Lobby(lobbyName, peer.id, mesh, single_host));
+		lobbies.set(lobbyName, new Lobby(lobbyName, peer.id, mesh, single_host, public));
 		console.log(`Peer ${peer.id} created lobby ${lobbyName}`);
 		console.log(`Open lobbies: ${lobbies.size}`);
 	}
@@ -206,7 +208,7 @@ function parseMsg(peer, msg) {
 	// Lobby joining.
 	if (type === CMD.JOIN) {
 		const dt = JSON.parse(data);
-		joinLobby(peer, dt['lobby'], id === 0, dt['single_host']);
+		joinLobby(peer, dt['lobby'], id === 0, dt['single_host'], dt['public']);
 		return;
 	}
 
@@ -224,6 +226,18 @@ function parseMsg(peer, msg) {
 		return;
 	}
 	
+	if (type === CMD.GET_PUBLIC) {
+		let pb = []
+		for (lb in lobbies.keys()){
+			if (lobbies[lb].public){
+				pb.append(lb)
+			}
+		}
+		const data = JSON.stringify(pb)
+		peer.ws.send(ProtoMessage(type, 0, data));
+		return;
+	}
+
 	// Message relaying format:
 	//
 	// {