802.11r Fast Transition how to understand that FT works?

Wired AP > Mesh > WDS

I only use the "Static address" protocol on the LAN interface of the dumb AP or mesh node, because the "DHCP client" protocol is unstable.

Something like this happened to me when I use the "DHCP client" protocol on the dumb AP or mesh node and it was fixed when I changed to "Static address" protocol.