Does anyone know a foolproof way of radio controlling a dozen arduinos? I'm working on a big project that needs about a dozen arduinos working with each other.

We had a train stand which was about 5 meters length and 2 meters wide. Each train had an arduino in it and was controlled via radio. To control trains we used zigbee.

Bluetooth could work for you. Depends on the area you need to cover

@zemaitis has the right idea here. For low speed, low power radio control zigbee is definitely the way to go.

@zemaitis @AlmondSauce I'll look into it.

@AlmondSauce Nobody mentioned low power or low speed.

@Ushandelukka At this point I'm open to any suggestions.

@Ushandelukka Arduinos don't have enough grunt to do anything but low speed, and being embedded devices, low power is almost always a plus too.

I should mention that in venue where this project is going to be used, bluetooth and wifi frequencies are going to have a lot of interference.

@AlmondSauce Well my arduino Unos working perfectly fine with the HC05/06 module @ 9600 baud. I am working with embedded systems on a daily basis but thanks for explaining.

You could try LoRa. Cheap, low power, ultra long range and easy but rather slow.

@JohnScott Zigbee uses the same frequency range as BT/WiFi so this could cause trouble. Maybe using a different technologie could be beneficial. Can you describe the prerequisites a little more?

@Ushandelukka The project is going to be used infront of a live stage and the venue is full of concrete and everyone is going to have phones. Worst case scenario I'm going to have to use a midi style connection with 12 volt cables and optocouplers.

@Ushandelukka You seem to be trying to pick a fight here when there isn't one... 9600 baud *is* low speed. Zigbee can cope with much more than that just fine.

Bluetooth would probably work too. (It can do much higher speeds than you're using there.) But the range isn't as great, and it's more susceptible to interference in my experience, hence I didn't initially recommend it.

You seem to be taking my recommendation for using Zigbee as a personal attack. It really isn't!

you could use MQTT if you have a Main Server which could bei use as Broker. this protocol is created for smaller devices such as smart home, arduinos, internet of things...

You'll need an external Bluetooth/WiFi module of some kind. For Bluetooth it's a complementary component, for WiFi it's replacing the Arduino with an esp8266 (more often than not it's sufficiently compatible and extensive in functionality as the Uno and such).

If you're going to expect lots of interference from other devices such as phones, it may be beneficial to use other frequencies such as that of LoRa though (but it's proprietary so that's a big no-no for me at least). Most 2.4GHz appliances are supposed to do fine in noisy environments though (think microwave ovens, WiFi routers all over the place, Bluetooth, wireless mice and such). This applies to most ISM bands actually, although 2.4GHz is the noisiest by far.