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I'm regularly hosting gaming events for medium-sized groups of 50-100 people. So far, players typically used personal hotspots to connect to the Internet. However, I would like to fix this with an AirPort Extreme setup. Before I purchase the equipment, I would like to answer some questions.

The target setup consists of two AirPort Extremes wired together to create a giant WiFi.

  • Do the two AirPorts create a shared subnet where every client can see each other?

    • If yes, what's the maximum size of that subnet? Is it just a 192.168.0.x one with 255 max-clients, or can you go bigger?

  • If people move from one AirPort to the other one, will they keep the same local IP?

  • Does AirPort Extreme support UDP broadcasting?

    • If yes, do these UDP broadcasts work between the AirPorts as well? i.e. if one client is connected through the first AirPort, and the other client is connected through the second AirPort, will they see mutual UDP broadcasts?

  • Each AirPort Extreme is advertised to handle up to 50 clients. Does this mean that I have to place the routers in a way that roughly halve of my people are in range of the first AirPort and the other halve is closer to the second one? Or will the connections automatically be balanced between AirPorts?

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    You don't have to use Airport Extreme here. Airport Express will handle the sub stations just fine, with only one master Airport Extreme. You could also use Linksys or some other brand of cheap router in place of Airport Express.
    – Daniel
    Oct 16, 2015 at 21:00
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    Problem with the cheap routers is, that they often don't support UDP broadcasting properly.
    – Etan
    Oct 17, 2015 at 6:39
  • True, but if you find one that does it's way cheaper.
    – Daniel
    Oct 17, 2015 at 16:13
  • Do you know one that's cheaper, runs reliably without any interruptions of any kind, supports UDP broadcasting, and supports 50+ clients at full speed over ac? ;) If not, then the comment is not really helpful, sorry.
    – Etan
    Oct 17, 2015 at 18:51
  • Also - I can't believe that no one else has voted this up as a good question. (although it only has 14 views - but two people felt it was good enough to answer).
    – bmike ♦
    Oct 17, 2015 at 20:14

2 Answers 2

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In 2020 - get a Dream Machine if you can. The software does all this automagically. Then add AP as needed to complete your coverage based on your measured quality and channel needs.

Your question is probably too broad, but a pair of recent 802.11ac AirPort extremes might actually run well with 50 clients. I would get a third for 75+ or if your clients aren't on 802.11 AC substitute 2 Express for each one Extreme to get adequate bandwidth over WiFi.

  • Don't place them all together on one table. The closer they are to the external walls of the room, the better your interference situation will be.
  • Do link them with cat 5e or better ethernet cable
  • The one connected to the internet is the router and you'll have plenty of reservations out of the box.
  • Set the rest up in bridge mode.
  • Run a wireless scan using airport utility on iOS or get a Mac program like WiFi Explorer so you can assign channels manually and troubleshoot things like spectrum noise to signal and channel overlap and utilization.
  • If all of your clients are Mac and iOS, and if you place the base stations equally around the space, toggling Wi-Fi off and on on the clients should do an acceptable job of balancing the load and matching each client to the closest base station
  • I would probably make different SSID for both 2.4 and 5 GHz and for each base station. You can make the password the same for all of them in that way if you need to go in and read distribute things you can.

If you set things up as I have described, you can choose and arbitrarily large pool of IP addresses, devices will retain the same IP address in general, UDP broadcast won't be a problem.

https://support.apple.com/en-us/HT202056

Set up the first Airport Extreme with Channel 11 and Channel 36

The rest go in bridge mode:

  • channel 6 and 153
  • channel 1 and 161
  • channel 11 and 157 (note 11 overlaps with the first - so make sure this is quite far from the first base station)

Avoid channel 149 since it's used initially for AirDrop/AirPlay. Don't use any channels other than 1, 6 and 11 on 2.4 GHz. If you have more complicated wifi planning needs, get a tool like wifi explorer to actually measure your network conditions in real time.

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  • Thanks! Could we maybe please verify that the UDP broadcast does indeed work across AirPorts before I purchase? If you have two AirPorts and are willing to build such a configuration, I will create two game accounts so we could try. Please open a chat session if that would be possible.
    – Etan
    Oct 17, 2015 at 6:27
  • @etan it works - I run this exact setup in many places. What specific port are you needing over UDP?
    – bmike ♦
    Oct 17, 2015 at 18:02
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    You're set then. One subnet, no firewall, have fun. If you want get two express for the remotes and set up channels per my edit. AC is the way to go if your clients support that. The express are nice if you have clients you want on 5 GHz, but not on AC.
    – bmike ♦
    Oct 17, 2015 at 19:47
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    Thanks. Purchased two AirPort Extreme, and the Nearby Discovery works perfectly in the game. Is there a guide regarding proper channel setups? Or is your suggested setup just coming from personal experience?
    – Etan
    Oct 22, 2015 at 14:38
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    @Etan I use wifi explorer to do my channel planning. It's something I do professionally and have some training from multiple vendors. I simplified the process to fit what I estimated as your requirements. Apple's wireless diagnostic is good too. Power off your base stations and see what channels it recommends after surveying your room. I'm happy your game setup works!
    – bmike ♦
    Oct 22, 2015 at 14:49
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What I would do here is get an Airport Express rather than a second Extreme. The Express can be configured to just repeat the WiFi rather than giving a second network. If you wanted to use an Airport Extreme, you could do this:

(From https://support.apple.com/en-us/HT202056)

Roaming Network (Ethernet-connected Wi-Fi base stations) Roaming Network

For 802.11n Wi-Fi base stations, creating a roaming network is by far the best choice. This will provide the best throughput between the base stations and your Wi-Fi devices.

This set up requires that your Wi-Fi base stations are connected via Ethernet.

The primary base station provides DHCP Services, while the extended base station will be configured to use bridge mode. All Wi-Fi base stations within the roaming network should use the same passwords, security type (Open/WEP/WPA), and network name (SSID).

You can add several extended Wi-Fi base stations to expand a roaming network.

You can incorporate a network switch if you don’t have enough LAN ports available on your primary Wi-Fi base station.

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    Good call on the link to Apple's setup. You can daisy chain the devices up to about 5 before the gigabit links would become saturated. Putting all the secondary AP into bridge mode is key.
    – bmike ♦
    Oct 16, 2015 at 21:07
  • Yeah, but you can also use more than one port on the main router for a total of 4 routers with a daisy chain length of 1.
    – Daniel
    Oct 16, 2015 at 21:08
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    Totally fill up the the main one and don't needlessly chain them, but for most budgets, they won't be doing 8 Extremes for just 100 clients. It's more about convenience of cable runs - hard to guess if they are on a football field or packed in a medium room without the OP explaining how many square feet of coverage is required/available.
    – bmike ♦
    Oct 16, 2015 at 21:12
  • True ^. But I would use Expresses instead of Extremes for the sub-APs.
    – Daniel
    Oct 16, 2015 at 21:13
  • @bmike: Everyone is packed in a medium room, but since one AP only allows for 50 clients, I'll have to go with a two-AP setup to allow for 100 clients.
    – Etan
    Oct 17, 2015 at 6:30

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