Utility is reporting acceptable speeds between units, so despite the red LED I think it's working OK:

@JeremyB7 

Thanks for your updates.

It is the display mechanism because there is a junior powerline adapter added into the powerline network. 

Per you said, it won't affect the performance, so you can be assured about it. 

Best regards. 

Thanks, the unit attached to the router has actually changed to a yellow/green LED - but other new 1000Mbps units elsewhere on the network are still showing red.

@JeremyB7 

Thanks for your reply. To further locate the issue, you ca unplug the AV500/AV600 units and plug the advanced powerline adapters (AV1000) into the electricity only, after that, please verify whether the powerline led still shows red. 

Still the same, try to reset them first and repair the AV1000 units only. 

Besides, does the remaining red powerline led affect the actual performance of the powerline adapters? Like the speed and stability.

Best regards. 

I haven't noticed any speed issues yet, but its early days. The red LEDs just make me suspect something's up - does a red LED signify that comms with the router is slow, or comms with ANY of the other adapters on the network is slow? And how slow is slow? The software utility shows red arrows for <50Mbps.

@JeremyB7 

Hello, the tpPLC speed is not the actual speed you can get from the powerline adapters. 

Per we discussed before, the red led light may caused by the junior adapters.

You can connect your computer to the powerline adapter directly to test the speed you can get. 

Best regards.