@Ric It is inexplicable (until someone figures out why) but changing WIFI ROUTER can address the fast flashing green MESH problem.
I'm not so sure the fast flashing green problem has anything to to do with IP6.
What I am sure of is that the mesh network is suseptible to something about the router used by it's gateway.
If you have another router or 5, try them in between your gateway and your "real" router.
That fixed this for me here::