Don't know the HW version, would be nice if it was on the case or displayed clearly in the app, but purchased 3 weeks ago from Amazon. 
 

Set a. Pack up a couple of weeks ago and it worked perfectly using Ethernet backhaul from a NetGeat switc for the satellites with Spectrum Docsys ET2251 modem. Even bought an M5 for the patio. 
 

After a couple of weeks of flawless operation. Lost internet connectivity with red lights all around. However the internet was fine when I connected my laptop directly to the modem.  With only the master X20 connected rebooting the modem and X20 would give me about 1 minute of internet before a red light and loss of internet. 
 

After many careful retries I decided the master must be bad.  I swapped for a satellite, reset it, and restarted from factory defaults. Once again things worked, but only for about 12 hours before it failed with red lights just as before. Once again a direct laptop to internet modem connection works fine as does my original Apple Airport router. 
 

I've put a half dozen hours into debugging this already. I'm an electrical engineer and not used to giving up, but I'm about to box this up and send it all back to Amazon. 
 

Is there anything else I should try or is the hardware just unreliable?