80 WiFi devices create lag

[ilyo]

Hello,

I have an Asus RT-AC68U router with the latest Asus-wrt Merlim firmware. We are a office and have about 80 mobile phones connected to the router. A lot use the LAN to do tasks. After 20 devices connect, all devices start lagging. The ping goes from 20 to 200-500 and sometimes drops.
What can I do make all the 80 devices work smoothly? Both CPU cores of the router do not cross the 20%. Almost all use 2.4G.
Should I buy AP's? Are there options in the router to fix this issue?

All help is appreciated.

Thank you.

 

[netware5]

Hello,

I have an Asus RT-AC68U router with the latest Asus-wrt Merlim firmware. We are a office and have about 80 mobile phones connected to the router. A lot use the LAN to do tasks. After 20 devices connect, all devices start lagging. The ping goes from 20 to 200-500 and sometimes drops.
What can I do make all the 80 devices work smoothly? Both CPU cores of the router do not cross the 20%. Almost all use 2.4G.
Should I buy AP's? Are there options in the router to fix this issue?

All help is appreciated.

Thank you.

Go to RouterGuide on this link and read about AMPDU aggregation and also other advanced settings. It will help you to tune the wireless to work in crowded environment.

 

[sfx2000]

Is the lag also observed on the ethernet ports?

80 clients on a single radio - might be running out of airtime on the 802.11 wireless channel

 

[Wutikorn]

Hello,

I have an Asus RT-AC68U router with the latest Asus-wrt Merlim firmware. We are a office and have about 80 mobile phones connected to the router. A lot use the LAN to do tasks. After 20 devices connect, all devices start lagging. The ping goes from 20 to 200-500 and sometimes drops.
What can I do make all the 80 devices work smoothly? Both CPU cores of the router do not cross the 20%. Almost all use 2.4G.
Should I buy AP's? Are there options in the router to fix this issue?

All help is appreciated.

Thank you.

I think setting will help just a little when there are 4 times of the number of devices maximum compared to number of devices when it starts to lag. I think business-grade access point designed to handle lots of devices is your solution. Since most of them are on 2.4GHz, it won't be too expensive to get single band AP. But I know little about business-grade AP, so you might want to check for maximum device a specific AP can handle. But turning on AMPDU aggregation as Netware5 suggests is the first thing to do . Also, having DHCP lease too short may also be a problem.

Edit: You can try increasing channel bandwidth to 40MHz which should help significantly as well as turning AMPDU aggregation as temporary fix.

 

[netwrks]

Time to consider Enterprise WAP's.

 

[thiggins]

Tweaking router settings isn't going to help. SFX diagnosed your problem correctly. You need more APs set up to properly share the load.

And don't enable 40 MHz bandwidth in 2.4 GHz, especially if you add APs.

 

[TonyH]

Hello,

I have an Asus RT-AC68U router with the latest Asus-wrt Merlim firmware. We are a office and have about 80 mobile phones connected to the router. A lot use the LAN to do tasks. After 20 devices connect, all devices start lagging. The ping goes from 20 to 200-500 and sometimes drops.
What can I do make all the 80 devices work smoothly? Both CPU cores of the router do not cross the 20%. Almost all use 2.4G.
Should I buy AP's? Are there options in the router to fix this issue?

All help is appreciated.

Thank you.

For that it calls for business class router/AP to have optimal result.

 

[ilyo]

First of all, thanks for all the replies.

Go to RouterGuide on this link and read about AMPDU aggregation and also other advanced settings. It will help you to tune the wireless to work in crowded environment.

- I have this setting already enabled and I believe it's enabled by default.

Will this WAP help? http://www.linksys.com/us/support-product?pid=01t80000003KO7WAAW
If not? Which would be the most price effective solution?

Thanks again

 

[ilyo]

Another thing that I wanted to mention that all the users are in the same room and all have full WiFi connection. So the range is not the problem. I have a few routers here that I can use as AP as well, will that help?

 

[thiggins]

Another thing that I wanted to mention that all the users are in the same room and all have full WiFi connection. So the range is not the problem. I have a few routers here that I can use as AP as well, will that help?

Yes. Make sure you set them on different channels, 1, 6, 11 only and 20 MHz bandwidth.
Since they will have no load balancing features among them, you may have to set different SSIDs and manually split up the 80 devices among the APs.

 

[ilyo]

Ok great, will try that tomorrow. Thanks

 

[CaptainSTX]

Ok great, will try that tomorrow. Thanks

To force everyone not to use the same SSID limit the number of addresses available in each APs to 25 - 30.

 

[ilyo]

To force everyone not to use the same SSID limit the number of addresses available in each APs to 25 - 30.

Really? So I should have at least 2 APs. Or 1 AP and the router? What's the best setup here?

 

[ilyo]

Which AP is better? Wap610n or tl-wa801nd? Thanks again

 

[Wutikorn]

Really? So I should have at least 2 APs. Or 1 AP and the router? What's the best setup here?

Which AP is better? Wap610n or tl-wa801nd? Thanks again

Unless APs are for enterprise, it probably can handle 20 -30 each, so I'm not sure what type of APs you have spare, or how many. Ubiquiti AP seems nice if you only have one router and one AP right now as the price is reasonable. As you only need 2.4 GHz channel, that will do. If you can't really control which devices connect to which AP, a way to help that is to lower transmission power a little, use the same SSID, and have roaming assistant enabled for both AP and router(put each on opposite side). Check if that Ubiquiti AP supports roaming assistant which should disconnects clients when signal is weaker than specific amount. Note that I have not tried any AP, but reviews should help you decide. You probably need two APs in addition to AC68U.

 

[thiggins]

To force everyone not to use the same SSID limit the number of addresses available in each APs to 25 - 30.

That doesn't prevent association. Clients will connect but won't get IP addresses and will appear to be broken.

 

[ilyo]

Yes, I think it would be better to have separate SSID so I can split up the load manually.

That doesn't prevent association. Clients will connect but won't get IP addresses and will appear to be broken.

Any idea on which AP is the best to use? Wap610n or tl-wa801nd? These are the ones I can get my hands on right now.

 

[CaptainSTX]

Really? So I should have at least 2 APs. Or 1 AP and the router? What's the best setup here?

If you already have the AP try using the AP and the radios on the router. If either or both devices have dual band radios try to get people that have 5 Ghz radios to voluntarily use those radios. For everyone else try and get them to use one or the other 2.4 Ghz radio.

If people don't or won't voluntarily cooperate then you will need to use your router plus another router double NATed behind it so you can have two separate DHCP pools.

With 80 clients for best possible connections you may need three sets of radios as the rule of thumb is 20 - 25 clients per AP radio. If a half the clients have 5 Ghz radios then you probably can get by with just two sets of radios. Not so much of a problem of processing power or speed as chopping each frequency up and it being shared by that many devices. Only one device or AP radio can be using a frequency at a time. Everything else needs to wait until the device using the channel finishes and received its ACK. With three sets of radios you can be operating on three 2.4 Ghz channels (1-6-11) and three 5. Ghz channels.

 

[ilyo]

Thanks CaptainSTX for your detailed reply. That is the answer that I was looking for!

Would I be able to have 3 routers and connect to all the devices via LAN using 1 PC?

For example:
Device 1, IP: 192.168.1.105, Connected to Router 1 via WiFi
Device 2, IP: 192.168.1.117, Connected to Router 2 via WiFi
Device 3, IP: 192.168.1.127, Connected to Router 3 via WiFi
Server 1, IP: 192.168.1.100, Connected to Router 1 via LAN

Can Server 1, connected via LAN to all 3 Devices?

Thanks

 

[CaptainSTX]

Thanks CaptainSTX for your detailed reply. That is the answer that I was looking for!

Would I be able to have 3 routers and connect to all the devices via LAN using 1 PC?

For example:
Device 1, IP: 192.168.1.105, Connected to Router 1 via WiFi
Device 2, IP: 192.168.1.117, Connected to Router 2 via WiFi
Device 3, IP: 192.168.1.127, Connected to Router 3 via WiFi
Server 1, IP: 192.168.1.100, Connected to Router 1 via LAN
Can Server 1, connected via LAN to all 3 Devices?

Thanks

Yes you want to connect all the routers/APs using Ethernet cables LAN port to LAN Port. If it is easier to setup you can string the APs together going from an Ethernet port on an AP to another AP. All the LAN Ethernet ports are available to plug devices into. If you want to enable everyone regardless of what Radio router they are connecting to use your server to just set the other routers up as APs and turn off DHCP on them. If you double NAT them you are going to have to create some routing tables to make the server available to all connected devices. I think it is doable but an added complication.

Ideally the Ethernet ports on all your routers APs are Gigabyte capable. If not then you will be better off plugging all the APs directly into your primary router.

You would just set up your DHCP pool on whatever router is your primary and ONLY router on your network. The device connecting will pull a IP from the pool somewhat randomly or if the lease hasn't expired the last IP it had. Keep the leases short so you can quickly recycle the IPs. Give your server a static IP outside your DHCP pool.

If you want to control what radios certain devices can access you can enable on each AP wireless MAC filtering. Tedious for you as system administrator as you will have to type all the MAC addresses in.