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I manage a student house with 10 bedrooms spread over 4 floors (basement, ground, 1, 2). There is a single ADSL line coming in to the basement.

Currently I have a modem/router (provided by BT, my ISP) in the basement, broadcasting wifi which the bedrooms in the basement and 1st floor can pick up. (4 people)

Wired from the back of this modem/router via cat5e cable is an access point on the 1st floor, broadcasting wifi which the bedrooms on floors 1 and 2 can connect to. (6 people).

The access point is set up correctly, I'm sure there is no configuration problems with the equipment, channels, etc. But the tenants complain of slow, intermittent internet access from time to time, probably peak hours. At no point does the wifi signal strength become weak, and at no point does the router in the basement indicate a problem with the connection to the ISP.

My question is, what is causing the slowdown? I cant see where there is a bottle neck in terms of the network and hardware. The only bottleneck that may exist could be a) the BT router being unable to handle traffic from the access point as well as the wireless clients when everyone connects at the same time? b) the ADSL connection being too slow to provide a service to 10 people?

Possible solutions are a 2nd ADSL line, or upgrade of routers. Which way would you go? The ADSL is approx 14Meg.

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3 Answers 3

To me this sounds like a concurrent connection limit on the modem itself. Most of these devices are capable of handing 512 concurrent connections. In my experience it usually takes 10-20 people to eat that up depending on the type of browsing that is occurring. If there is any peer-to-peer activity this will be consumed much faster. Check the status page of the AP and modem to see how many connections there are. You may have to replace these devices.

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Could also be channel crowding; EMI; or a million other things. –  Chris S Dec 8 '11 at 14:10
    
Thanks for the help Paul. As far as I'm aware, its just basic browsing occuring. But I suppose if you add in that each student has a mobile phone on wifi too, this could add to the number of connections? As far as I'm aware there is no peer to peer activity though. I think I will replace the BT router and the access point 1st, and if the problem persists, install a 2nd ADSL line so I can separate the traffic from the lower 2 and upper 2 floors entirely. One factor I cannot account for or control is inteference from nearby wifi, suppose this could be a factor too. –  AMJ Dec 8 '11 at 14:15
    
I would recommend that you verify connection limits as the problem before spending $ since you wanted to keep it cheap because as others have mentioned it could be something else. Regarding interference, really simple tools to see what SSIDs are in range include airodump(nix) or netstumbler(win). You can verify how many other networks are in range and on which channels they are operating. I doubt that you have an interference problem with your N router upstairs though as there are many more channels and much less interference. –  Paul Ackerman Dec 8 '11 at 15:12
    
Also most routers will have options to block peer-to-peer traffic. You should jump in, make the change and see if the problem persists. –  Paul Ackerman Dec 8 '11 at 15:13

You say students, I hear uTorrent uploading all it can.

Get some sort of router that can limit the upload equally amongst the users, prefferably with TCP ACK prioritizing since you're using ADSL. Or get a symmetrical connection, since you're sharing this with alot of people.

I doubt that this is a wireless problem, but you could invest in Cisco 500 SMB AP's who can cluster (as in share configuration and channel optimization). They're not expensive.

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Hehe, well I've asked them all if they download movies, or use a lot of iplayer and youtube, and they say no. Could be a closet torrenter amongst them I guess! I'd be happy if anyone can recommend a router to try. –  AMJ Dec 8 '11 at 14:34

For a start, wireless bandwidth is a shared medium. Take your 54meg and devide it by the number of clients (4 and 6 respectively). That's not allowing for poor reception, and all the usual pains of using wifi. (i.e: are these access points on the same channel interfering etc).

Also, as paul said, p2p traffic will likely kill it stone dead due to the number of connections.

.. and you may have upload traffic choking the connection, which may be fixed by bandwidth shaping and traffic control (tc, in the linux world).

14mb is plenty, many offices run 10mg for 100's of staff, allbeit not all on youtube.

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Thanks Sirex. The router in the basement is wireless G, but the 1st floor access point is wireless N, so supposedly more bandwidth? Reception is pretty good everywhere in the building, and the 2 routers are on non overlapping channels. City centre = neighbouring wifi though, possible inteference there :( –  AMJ Dec 8 '11 at 14:19

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