Sorry, but it is incrementally getting really annoying... It's about a month now...!

Topography:

I have 3 deco units around the house - in a wide triangle formation, i.e. the wifi-mesh area - that would be A↔B↔C).

Single floor/level apartment about 160sq m overall. End to end. Triangle era covers about 3/4 of that.

Deco Settings:

1. Deco is the (only) dhcp server,
2. 2.4Ghz/3GHz enabled (some of my devices need 2.4GHz)
3. IP4/IP6 enabled, 
4. SIP AKG enabled,
5. Fast Roaming: Enabled
6. Beamforming disabled, (not that it made a difference)
7. Operation Mode: Wirelsess router

Troubleshooters I already tried - as suggested elsewhere by Tech Support and others

1. Swapped decos main/etc
2. enabled / disabled / changed all advanced settings. Tested for about half a day with each setting combination (it's been a month+ after all...)
3. Dedicated IP address to the two devices, No luck

Description:

My 'mobile' devices keep disconnecting when moving around the house. My 'stationary' devices remain connected, duh!

So, my desktop, in a fixed location remains connected.

So, I pick the tablet (or mobile phone), in proximity to point A and then move closer to point B. Then the device keeps disconnecting/connecting. In order to get a steady signal I either have to disable wifi/wait 10sec/renable wifi, ;or wait for maybe more than 5, sometimes 10 reconnects before the wifi signal locks. 

I'm sorry to say but this is suspiciously like a plain wifi-extender problem.  I mean in a mesh network the whole idea of mesh is that you remain connected anywhere within the mesh!!!

Same happens proximity changes between A↔B or A↔C or B↔C. 

It gets worse (the number of disconnects/reconnects increases) the closer you get to a(ny) deco unit.

So something is seriouly wrong with the P9's mesh-tech ... it's messed up!

What do I do?

The product is not functioning as advertised, that's for sure.

And i shouldn't be a network expert in order to use it; even if I know how to that. 

Thank you in advance for your insights.