SHP-DR708BU/CN and Smartlock App Doesnt connect

Now that I have successfully created account and registered my lock via WiFi, the app doesnt not reflect any of my door access. when i select to remotely open the app, it didn’t work and show "Bad Gateway (B0502), what does that mean?

Also, the Samsung Smartthings app cannot control the lock either, what is wrong?

Help please.