POST Method not working

I have uno + sim800 shield + em506 stack together already finish the where it has sending sms, auto responder when texted, sending data to server.The code is working when I use serial monitor when running the script but when I use only the external power for arduino the POST method doesn't work but the sending sms and auto responder works fine. Anyone had this problem before ?

Show the sketch please.
And ensure you use CODE TAGS ( </> )

n3mub:
when I use only the external power for arduino

Which is?

Whandall:
Which is?

USB to DC 9V hook up to an power bank

Why don't you connect the powerbank directly?

It is connected directly

Then I do not understand "USB to DC 9V hook up to an power bank".

There is no 9V involved in USB or powerbanks normally.