The client:

private val serverRoomListener = object : Room.Listener() {

    override fun onLeave() {
        Timber.e("leave")
        task = object : Timer.Task() {
            override fun run() {
                ServerClient.getInstance(ServerClient.Builder(url = SERVER_WS)).also {
                    it.setListener(object: Client.Listener{
                        override fun onMessage(message: Any?) {

                        }

                        override fun onClose(code: Int, reason: String?, remote: Boolean) {

                        }

                        override fun onError(e: java.lang.Exception?) {

                        }

                        override fun onOpen(id: String?) {
                            val rejoin = it.rejoin(currentRoom.name, it.id)
                            if(rejoin.hasJoined()){
                                task.cancel()
                            }
                        }

                    })
                    it.connect()

                }
            }
        }
          Timer.schedule(task, 10f, 0f, 0)
    }

Timer tick delay 10s

The server "colyseus": "^0.9.32":

onJoin(client, options?, auth?) {
    console.log(this.getLogTag(), options, auth, client.id);
    if (options.create) {
        this.state.masterPlayer = client.id
    } else {
        this.state.slavePlayer = client.id
    }
    console.log(this.getLogTag(), 'Client joined: ' + client.id);
    if (this.clients.length == 2) {
        this.lock();
        this.state.state = State.GAME;
        let command = {};
        this.clients.forEach(function (value) {
            command[value.id] = {}
        });
        this.state.command = command
    }
    this.broadcastPatch()
}

    async onLeave(client, consented?) {
        try {
            if (consented) {
                throw new Error("consented leave");
            }

            console.log(this.getLogTag(), "Count users:", this.clients.length, consented);
            await this.allowReconnection(client);
            console.log(this.getLogTag(), 'Reconnect client: ' + client.id);
        } catch (e) {
            console.log(this.getLogTag(), 'Error: ' + e);
            console.log(this.getLogTag(), 'Client left: ' + client.id);

            if (client.id == this.state.masterPlayer) {
                this.state.masterPlayer = null;
             //   this.unlock()

            } else if (client.id == this.state.slavePlayer) {
                this.state.slavePlayer = null;
         //       this.unlock()
            }
        }
    }

reconnection server log http://prntscr.com/mvsyas

Thanks for help.

I've seen you are using Kotlin, did you make your own version from doorbash's library? I'm interested in your Kotlin lib :)

Thanks