Q: airport express cannot connect to airport extreme

I have one airport exttreme as my main network hud and have two express connected to the network to extend it.

Suddenly both express has stopped working and Airport tool cant find them unless I reset.

When updating the expresses they dont connect and disappears from my list.

The network has been working fine for many years but suddenly stopped.

I cant think of anything that have changed.

Help!

Staffan Lund