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Hi I am having some problems with creating a decent office wifi setup. This is the current setup:

Users via Wifi x15 > Router wired into > Airport Extreme wired into > Phoneline

So our 15 concurrent users connect to the router (wireless) which is then wired up to the Airport Extreme which carries the data via ADSL wire into the phone line.

When I am the only one here the speed is staggeringly fast (as expected), but when 5 + users join the network, it becomes horrifically slow. When all 15 of us are here it is almost non-existent. This is expected to a small extent but we got the Airport Extreme due to it's 50 user capability and figured this would be fine since we would only have maximum of 15 users connected.

What have I done wrong (if anything?) and what can I do to get the best speeds with 15 users?

Please let me know if you require any further information on the setup.

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Why do you have the separate router? The AirPort should handle that. –  Joel Coel Mar 28 '13 at 16:29
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Just add a second access point. Also, you should make sure that nobody is using a device that only supports slower bit rates (802.11b) they will slow everyone down. –  Zoredache Mar 28 '13 at 16:29
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You should not allow 802.11b users to connect period.. if they have a device with b only, tell em to upgrade.. or set up a separate AP for them. –  NickW Mar 28 '13 at 16:32
    
All of us use macbook pro, macbook air, or a medium to top range windows machine. Not sure if that helps? –  Graeme Mar 28 '13 at 16:56

2 Answers 2

Why do you have an additional router connected to the AirPort? It seems like this would, if anything, hurt your throughput.

Supporting 50 users is a strange claim that has limited basis in reality. The limiting factor in wireless routers has very little to do with the number of users, and a whole lot to do with Air Time.

Imagine you are in a crowded room, and everyone is trying to talk at the same time. Most of the conversations involve the same individual... he's the guest of honor. Fortunately, this person talks very fast, but he has an odd limitation: he can't talk and listen at the same time. If he needs to listen to someone who speaks very slowly, that eats up a lot of time that could be spent communicating with others. Additionally, as more people come into the room, not only does he have less time to spend talking with each person, but the total amount of information he is able to share with the group decreases. This is because he has to spend time in introductions, and in picking up where he left off as people come and go, and especially because people tend to interrupt each other more and more as more of them vie for his attention. It also doesn't help that the "room" has very thin walls, and outside noise often causes people to need to repeat themselves.

That's how wireless internet works. One router, even a very bad one, could support 1000 people if each person doesn't need to talk much. But if a few people want to engage in non-stop chatter — think: bittorrent, streaming media (youtube, netflix, pandora), large file downloads, skype/facetime/google hangout chats, etc — then the router may only be able to serve a very few people.

Here's the other problem: adding more routers often won't help. There's only so much air time available before you have too many people talking over each other. It's easy to reach a point where people have to repeat themselves (retransmit packets: this is handled by your network cards automatically) so often that the total amount of information shared is degraded significantly.

Supporting "50 users" is a marketing attempt to translate technical information into something the non-technical users can understand, but it really has only a limited basis in reality. It is a good rule of thumb that an access point can support 25 people per radio. The AirPort Extreme has two radios (one 5ghz and one 2.4Ghz), and so you get 50. Note that this won't help if all of your laptops only support 2.4Ghz, which is very common, and again: it depends greatly on the nature of the traffic involved.

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That was my original thought. I was not the person who originally set it all up, I've just inherited the problem ;) so just seeking some professional advice. It seems the airport is using it's HDD capability for secure network files. Perhaps this was the reason. As mentioned above traffic includes, youtube, page views, dropbox, emails. So essentially the airport is being used as a bridge. (I think, sorry I'm new to this) –  Graeme Mar 28 '13 at 17:00

It sounds like it is just a limitation of your internet connection which I guess by the way you describe as "phone line" is an ADSL line and hence has a relatively low upload speed and possibly a slow download also depending on where you are located geographically.

With no-one connected you can check the speed of the line by going to e.g. http://www.speedtest.net/

Once you have this you can decide if its enough for the sort of things your users are doing.

What are your users doing?

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Its most likely this. You should bite the bullet and get a T1 line installed –  VBwhatnow Mar 28 '13 at 16:50
    
Typical usage would be youtube, page views, dropbox, emails. –  Graeme Mar 28 '13 at 16:57
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@VBwhatnow A T1??? 1980 called and wants their technology back. 15 users on a T1 works out to about 100K bit /sec each. Business class cable or DSL connections provide much more bandwidth, and much cheaper than a T1. –  HopelessN00b Mar 28 '13 at 18:18

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