I am using nRF24L01+ transceivers to provide wireless control for oo Gauge model trains. The transceivers are very cheap and effective and I think the program code for them would be much simpler than using WiFi, a webserver, etc.
I got my nRF24s working with this Tutorial
The pair of programs in this link may be useful. They are derived from my train control program. The master program can be extended to communicate with several slaves. It may also make more sense in some situations to put the master program in the train.
They require the TMRh20 version of the RF24 library which solves some problems from the earlier ManiacBug version
...R