Multiple Devices Showing as Offline when they Aren’t

Hi

I purchased 4 Eero devices (standard, not pro or beacon) yesterday. Today I installed all four, which are all wired in via Ethernet. 
 

the signal strength is fantastic everywhere and I am very pleased with the results. It has pretty much tripled my WiFi speed too. 
 

my only issue is that, out of 51 connected devices, around 17 are constantly showing as offline when they are in fact online and working fine (lights, cameras, phones etc). 
 

I have restarted the entire network from the app but they still show as offline (some of them show activity when pressed in the app too which is also weird). 
 

Does anyone have any advice on this?

Many thanks

Jim