Thank you all for your valued input -much appreciated !.....Yes- certainly ,sounds like the extenders causing this .
Connecting direct to the Amplifi router , this never happens .
What is confusing is this happens on both extenders..........One is an Amplfi Mesh HD unit so made to work with...
Have reset both mesh extenders - same.
Works Ok for a while on all devices and then on a device at random to 10.10 etc with no internet .
Reset the WiFi and reverts back to correct IP address.( for a while)
Not cloud managed ,no.
To attempt to correct prior to a reset want to manually insert...
So ....,here is the issue - my Amplifi Aliencurrently has Google DNS of 8.8.8,8 . It has no option of a dynamic address setting . . How it got there I cannot say .. To see whether this will use the MWeb address automatically appears I have to reset .
I have today changed DNS to 1.1.1.1. Reason...