I recently bought a Deco M9 Plus. Set up was ok and everything works well. After 2 weeks I could connect remotely via my app" 

the message is " we couldn't find Deco. Something went wrong with the cloud service "

I can connect to my network whilst at home. 
 

I tried power off and off the main deco and turn on/off the Dynamic DNS but all these couldn't work. 
 

any advice please. Thanks in advance.