I have Arduino Uno and Arduino Ethernet Shield. I have four sensors. I am reading sensor values and post it to an ip address. Everything works fine. But my problem is about power supply. When i plug usb cable from any PC to Arduino Uno usb port as power supply, everything is fine. But i want to feed my boards with adaptor that outputs 9V, 1A and available for Arduino Uno. When i use adaptor as power supply, my http post method is not working. I measure all the outputs and inputs of all components, then everything is fine again. The problem is about Ethernet Shield i think.
What is the difference between feeding from usb and feeding from adaptor? Codes are the same just the feeding is changed.