Thread Safe Singleton Class - Am I doing this Right?

I am creating a system state class that needs be thread safe in reading/writing. I am implementing it using the Singleton Design Pattern. I have based it off of pointers from these Stackoverflow questions:

1. Singleton: How it Should be Used
2. C++ Singleton Design Pattern

Here is a condensed example of my code. Essentially it is just some state variables I need to keep track of and share across several threads. I know for a fact there will only ever needs be one state instance and I know that it needs to thread safe and constant. Will this implementation ensure that?

// System_State.h
class System_State
{
public:
    static System_State &getInstance()
    {
        static System_State stateInstance;
        return stateInstance;
    }

    System_State(System_State const&)   = delete;
    void operator=(System_State const&) = delete;

    // Example Setter with mutex guard
    void setWifiConnectedStatus(uint8_t _status)
    {
        std::lock_guard<std::mutex> lock(mtx);
        Wifi.ConnectedStatus = _status;
    }

private:
    System_State() 
    {
        initializeState();
    }

    void initializeState();

    std::mutex mtx;

    static struct WifiService
    {
        uint8_t     ConnectedStatus;
        std::string CurrentConnection;
        std::string SavedNetworks;
        std::string AvailableNetworks;
        std::string ForgetNetwork;
        std::string ConnectTo;
        std::string DisconnectFrom;
    } Wifi;

    static struct ScanService
    {
        std::string PerformScan;
        std::string ScanStatus;
        uint8_t     ScanProgress;
    } Scan;

    static struct UploadDataService
    {
        std::string PerformUpload;
        uint8_t     UploadProgress;
        uint8_t     ItemsWaitingToBeUploaded;
    } UploadData;

    static std::string LEDControlBrightness;
    static uint8_t     BatteryPercentage;
};

And here is some example main

//main.cpp
#include <thread>

void loop1()
{
    System_State state = System_State::getInstance();
    while(true)
    {
        //do randomness with state
    }
}

void loop2()
{
    System_State state2 = System_State::getInstance();
    while(true)
    {
        //do randomness with state2
    }
}

int main()
{
    std::thread t1(loop1);
    std::thread t2(loop2);
    // do and join and all that!
    return 0;
}