Airport express keeps loosing connection to Time Capsule

For several years I have had no issue with mt Airport Express staying connected to my Time Capsule/router. Now 2 of my Airport Expresses keep loosing the connection and flashing yellow. I have done the resets where I press in the little button on the bottom while plugging the AE back into the power source and reconnecting through Airport Utility and that will do the trick but after a short time the flashing yellow lights will go back on.

Would it help to turn off the router, rest all the AEs? It is so frustrating to keep loosing the connection and nothing else has changed; e.g. the AEs are all in the same place.