@Gordon_Taylor 

Hey

The 4010P kit is the older homeplugs and from experience these are known to be susceptible to interference.

Have these been working before or is this a new install?  

It it was working before, try disconnecting all possible plugs overnight as it could be static on the circuit... reconnect in morning and test.  I have seen this more than enough times fix this :)

If its a new install, then is your upstairs on a separate breaker or circuit?   modern breakers and trips can stop these working.   If so you might be better looking at a wireless solution, something like hte DECO M4

@Philbert 

yes they were working perfect then just dropped out. 
tried what you have suggested but to no avail, just weird that connect when both downstairs but not upstairs. 
 

thanks anyway. 

@Gordon_Taylor 

Umm that is a strange one!  How old are the devices?   It simply could be that they are now failing.

I had a friend used homeplugs (same model as yours) for years, then they just started to get slower and slower, eventually would only work over a short distance like yours.   He replaced them with the faster AV2 standard (100mbps+) and it worked again.   Just put it down to failing devices.