@stevei 

Hi,

If you swap the two TL-PA7010 Powerline adapters with each other (i.e. plug the second TL-PA7010 into the wall socket where the first TL-PA7010 normally is and the first TL-PA7010 into the socket where the second TL-PA7010 was) does the problem follow the particular Powerline adapter or not?

In case the problem follows one particular TL-PA7010, then this one must have somehow developed a defect. 

  @stevei 

Hi woozle

Thanks for the reply. I have 4 devices, 3 in use. I have swapped them all around and it makes no difference.

  @stevei 

By "it makes no difference" you mean the problem stays at the same location (i.e. same room), no matter which one of your TL-PA7010 devices is plugged in the wall socket of that room?

If yes, then what type of Ethernet cable do you use at that location? Mainly, is it shielded Ethernet cable or unshielded Ethernet cable? (this can be identified by the printing on the cable, like shown in the picture below)

Have you already tested whether using a different cable makes any difference?

  @woozle 

Yes, I have changed the cables and moved devices and the problem still persists in the same location. I am thinking of the possibility of some kind of noise or interference on the mains circuit. 

  @stevei 

Are there other electric appliances plugged into wall sockets adjacent or near to the one where the problematic Powerline adapter is plugged into?

If yes, then disconnect those other electric appliances for a moment and check if the Powerline problem persists.