This is going to break your rule about the 2.4ghz for home and 5ghz for work.. but humour me for a trial.
Use a different wireless name on 5ghz in the Extreme.. when you connect the Express in wireless extend mode.. use the 5ghz band.. the Express assuming it is new type will use 5ghz for back channel and can extend both bands.. so you will then see 2.4ghz produced from the express. See if that is stable.
My problem is that i continue to get amy drops on both 2.4 ghz.
It is unlikely both the FIOS and the Extreme are faulty.. this is more likely interference from so many wireless devices in apartment building or near neighbours.. this band is now jammed with equipment.. no just wifi.. there are DECT phones, (they use 10x the wireless output power cf wifi), front door bells and cameras, hifi senders, infrared extenders, baby monitors.. you names any wireless stuff.. and it is just as likely to use 2.4ghz.
What makes this harder is most of these devices will not show in a wireless analyser.. since they are not network.. you need wireless spectrum analyser which is whole different beastie.
