@Seyeclops 

I have M9s in my Deco mesh and I can reassure you that every Satellite Deco shows devices connected to it. Main Deco only shows devices connected to Main Deco.

I will need additional information from you, if you want me to figure where the problem could be. Please share screenshot of "Update Deco" page from Deco app, which will tell me what firmware versions your Deco units have. If firmware is very old, such as 1.2.*, this could be a problem.

Example:

Also, just to make sure your Deco mesh is properly configured, all Deco units are online and healthy, please share "Show Map" screenshot from your Deco app.

Example:

By the way, from that screenshot taken from my Deco app you can see Satellites (Office and Bedroom) reporting devices connected to them, in addition to Main Deco (Living Room).

  @Alexandre. Thanks mate. 
 

it looks like the main deco is only 1.2 - but I have regularly updated so I don't know why this one is different from the others. 
 

I can't find how to show the configuration - as you showed in your second image. It used to show but I can't find it now. 

  @Alexandre. Thanks. I will try this in the morning and hopefully it will fix the problem. Your help is very much appreciated. 

  @Alexandre. I am unlikely to get time to do this for several days (as the work laptops in the house won't allow me to download the software due to security - so I will have to get my mac from another location) but one thought just occurred to me. As all the other deco M9s seem to have been upgraded to V1.6 - can I just use one of these deco units and swap it for the main unit (and then make that the main unit) - and then resolve the issue with the one M9 when I get time? I have more than I really need anyway. 

  @Seyeclops 

You can swap Main Deco, and this is the workaround I was going to suggest if upgrade will fail. There is just one thing: you can't buy new M9 Plus in single units, only in 2-unit and 3-unit sets. Which means, if you bought them new you should have more than one M9 Plus with firmware 1.2 in your Deco mesh. 

So, yes, go ahead and swap Main Deco with different Deco unit, here is the process: Changing the Main Unit for your Mesh Network

Choose Satellite Deco you bought the last, chances are it will have 1.6 firmware.

After successful swap, check in Update Deco that new Main Deco has firmware 1.6. If yes, check if now devices are reported as connected to Satellites. If not, remove all Satellite Decos with firmware 1.2 your Deco mesh, this is how: How Do I Reboot or Reset My System?

Follow Reset a Deco unit section from that document. Do that for all Satellite Deco with firmware 1.2.

  @Alexandre. Thanks. I will try this at the weekend and hopefully let you know it has all worked out. Thanks so much for your help. 

  @Alexandre. 
 

I have replaced older deco M9 v2 plus with one of the newer ones and made it the Main unit connected to the Virgin router. The 3 new units are now updated to 1.62 (although one of the images attached does not suggest that - but they are) but the 3 older units will not update. I have removed them and added them back into the system but nothing seems to work. . I have tried to connect to one of them with an Ethernet cable but it will not even open the web management login. 
 

i have removed the older devices again and just added the one in the office - as you see with the photos attached it has not updated and appears not to have any devices connected. 
 

I presume my only option now is to replace the 3 older units? Add them one by one and hope they are all updated and will update in future?

one final thing. If I was to replace the whole M9 Deco Plus system (I can get my work to pay for it) what is the best home system with WiFi 6 that I could buy to replace the M9s? For example X60 AX5400? 

And if I just remove all the m9s should I be able to start again with a new main unit and add as many additional units I want?

 Will attach some more photos to another reply as struggling to attach to this post. 

thanks. 

  @Alexandre. 

  @Alexandre.