Rare for me to post, hoping someone may be able to assist. I have a multi-generation airport network (image below). Airport Extreme AC= primary base station. Airport Extreme N, and two versions of Express N are all extending the network. (3 total). Extending works however dropouts are extraordinary. I have reconfigured each device multiple times, modem is fine. I am reflecting that it may simply be inadvisable to mix generations such as this, however it should theoretically work. Any thoughts very welcome (I am using the older express N inside a portable speaker, very nice and would like to keep it part of the network if possible, however it may be a major cause of issues given its age). The other (newer, current gen) express N serves as speaker base for another audio system. I sincerely appreciate any input into this matter, very sincerely yours- Brom.