Thinking what's best 

Set static from PlayStation 

Set static from Router 

set static from Deco Ap ( would be handy )

@Rocco48 

Depends on what mode you run your Deco mesh.

Set static from Router - if you run Deco mesh in Access Point mode

Set static from Deco app - if you run Deco mesh in Router mode

@Alexandre. 
 

Router mode 

So setting from Deco Application on my phone will do the job , save me going near settings on his PlayStation 4.

Im going to run a Cat6 cable from Deco to his PlayStation as well .

So address reservation is same as static mode ( seems obvious) .

cherers bud .