ethernet connection airport express and airport model A1088 and A 1264

Dear Bob Timmons, I read your very clear and helpfl instructions how to configure an extended network through an ethernet cable between the airport extreme and the airport express. I followed your instructions and initially it all worked perfect. But after a few days not anymore.

This is our configuration:

Airport Extreme (802.11n third generation, version 7.6.1.), an airport express, model 1264 and 2 airport express model A1088.

You wrote somewhere "that the old models A1088 and A1084 do not have the capability to "extend" a wireless network, so they would not be compatible with the AirPort Extreme for this purpose".

Does this mean that even when connected with an ethernet cable they can not extend the network?

Thanks in advance for you answer, or someone else..

Greetings from Italy, Bellatosi