Weird HM-10 Behaviour

The exact same HM-10 would not work on the Arduino Uno but it works on the Nano with the exact same code and wired to the same pins.

I have tried swapping out the HM-10 to another one to rule out a faulty HM-10 even if I do not think it is faulty as it works on the Nano.

I have also tried swapping out the Uno in case it is faulty. I've also used the SoftwareSerialExample to send AT commands and it returns OK on the Nano but not on both my Uno.

Arduino > HM-10 (Baud 9600)
5V > VCC
Pin 8 > TxD
Pin 9 > RxD

I have tried both SoftwareSerial and AltSoftSerial with the same baud rate as the HM-10.

I am out of ideas and explanations as to how this can happen.

Anyone care to offer any insights? Thanks

Can you post the code you were using on the Unos? Did you change the board option from nano to Uno in the Arduino IDE before uploading to the Uno?

The Nano has a few differences compared to the Uno.
One is a lower supply voltage (4.6volt) on USB (and because of that different digital switch points).
Another difference is a weaker 3.3volt pin.
More info needed.

Thanks for the replies. I sorted out the problem. It was a silly one. One of the cables used for TX/RX was faulty on the Arduino UNO. This caused me hours of grief. I was thinking too complicated. Sometimes we just have to think simple.

Thanks for the help nonetheless