Hi,
I have had the same experience twice, at two different homes, with two different connected modem-routers.
The most recent experience involved FOUR Powerline adapters, all the same (version 2.0 hardware with default firmware). The adapter connected to the router disconnected and would not reconnect (pair), either using the utility or using the "pair button" technique (from any of the other, still-connected Powerline adapters).
The LEDs showed that the adapter in question was disconnected (from Powerline network) but was ON and was connected to Ethernet.
When I cycled power to the disconnected Powerline adapter, it simply started working! Already connected. Nothing to do.
I used the utility to check that bandwidths across the home. All of the bandwidths to the adapter in question were between 100 Mbps and 300 Mbps... so it was definitely NOT due to a marginal signal.
The adapter in question was NOT in sleep (power-save) mode. One of the other adapters was (because I had disconnected its Ethernet port)... so I am dubious about the suggestion that the fault is related to the power-save mode. However, I will disable power-save mode on all FOUR adapters and monitor them.
I have to say that otherwise, the adapters are excellent; the utility and firmware update processes are excellent; the documentation is good. However, reliability is key. I look forward to hearing about a newer firmware update because the latest update is dated 2013 or 2012.
We were going to use these adapters for a commercial purpose (and therefore buy many of them for our customers' premises) but now, we cannot afford this risk.
I trust that TP-Link will help because their support has been excellent!
Comments welcome!
Clek.

@UniQue1992 

Seems like this is still a thing, however when I turned off the power saving mode, I still get disconnected and have to replug my lan cabel to the PC. :/