@UnWired 

The red LED means the powerline connection is below 50 Mbps, this could be due to distance or the electrical noise over the line. The powerline network only works while on the same electrial panel, another house can not tap into it even accidently.

The powerline light will need to be on in order for it to be able to transfer data, if the LED is off, neither red or green then it is not connected to anything.

@Tony 

Thanks.  Appears that there is no "added value" from pairing, especially when I seem to have so much trouble doing it.  "Red" in my particular case, seems to mean more than simply "Under 50mb".  When my adapters "Go Red", there is no network connection between ANY of them.  And, waiting doesn't make it come back.  In contrast, the tpPLC utility program will show a link drop below 50mb occasionally, and then a few seconds later it is higher.

What I have done (in desperation) is set up a "Ping Monitor" on my desktop computer that pings a couple of IP cameras across the PowerLine link. When two pings in a row get no response, it sends me an email and I go look at the lights.  This last time, I rebooted my desktop after a Microsoft update and forgot to restart the Ping Monitor. Was blissfully ignorant until the wife said, "How come I can't see who's at the front door on that security app?"

In a different forum, someone commented that the Broadcom Home Plug AV2 chips have a flaw that has not been corrected for years.  He claimed that Home Plug AV2 with the Atheros chip is actually "faster" then the supposedly higher performing Broadcom chip.