Arduino Nano pin 30 power issues

I have an arduino nano that is in charge of opening and closing a relay. I am powering it via pin 30 with a 9v plug in power supply (2A). When powered this way it will not open the relay when prompted. When I instead power it via usb it works just fine. Does anyone have any idea why this is? I took a volt meter to all pins and they work.

pin 30 has 9V
5v pin has 5v
3.3 has 3.3

The cause can be many, but perhaps it is one of these:

  • The relay could be used in a wrong way. Please show us a schematic and all the info about the relay.
  • The voltage regulator on the Nano board could have trouble with the relay. Regardless the voltages you measure, there could be a voltage dip when the relay is activated.