I used a powerline adapter like this to connect my security camera receiver to my router. This allows me to access the cameras from my cell phone which was working but now it doesn't. There's two things that may have caused this. 1. The receiver was unplugged for a while which may have affected the settings on the receiver. 2. The other powerline adapter was moved to a different circuit.
The settings on the security camera receiver look fine although it's possible the ip address changed and the phone may need to be re-connected.
I know the easy answer here is just plug the powerline adapter back into the old outlet. Unfortunately that outlet was removed because it wasn't code compliant.
Edit: Photos of the panel showing the which circuits the powerline adapters were/are now plugged in to.
Best Answer
I did the unthinkable, and started to read the manual for the product you linked, and in the troubleshooting section there is a theme:
If you search the PDF for "circuit" you find this phrase several times. I didn't find where the manual lists using the same phase or circuit as a hard requirement, but you can infer from the troubleshooting that they fully expect you to use the same circuit, which I think is a "dumbed down" way of saying it should be the same phase/leg.
I also found this in their FAQ section:
I think they are being a little concervative, because I do have powerline adapters on different breakers, and they work reliably.
Netgear is more optimistic, which muddies the waters a bit because most of these devices are based on the same protocols and theorys:
Finally the Homeplug (standard the devices use) wiki page states:
In conclusion, the answer appears to be a big "Maybe".