D-Link DHP-P600AV Ethernet over powerline - Losing ethernet connection

I've recently purchased a D-LINK PowerLine AV2 1000 (DHP-P601AV) Gigabit Passthrough Kit (from Harvey Norman) for use in connecting lounge modem back to home office 8-port ethernet switch.

A couple of times since install it's dropped connection, & connected devices report "No internet"

Photo is of current state of the device:

From the product manual it advises (from top down):

1) Ethernet LED on Both = Solid: The Ethernet port is linked

2a) Powerline LED on Lounge (connected to modem) = Red: The powerline link rate is fair

2b) Powerline on Office (other end of connection) = Blinking Red (The powerline link rate is fair) & Green (The powerline link rate is excellent)

3) Power LED on Both = Solid: The device is receiving electrical power

I've tried both reconnecting & resetting both power (in correct order), but get same result on both. Also tried resetting the modem with no change to service.

Does anyone have any experience in resolving this issue, or any other advise for these devices?

Thanks in advance.