WIFI problem at Bridge club

[think2]

At my Bridge club we have a cheap Lenovo tablet at every table for scoring. Sending the score from the tablet to the master nearly always works but the info that gets sent back after the score has been sent quite often fails to arrive at the tablet, it’s probably a longer message. Switching airplane mode on and off turns the wifi off and on and the tablet usually then receives the info from the master - but it can go wrong again before long. There’s anecdotal evidence that the smaller number of tablets in play the less connection problems there are.

I don’t know the exact model but I think it's the "A7-10 Tablet 3" and were bought two years ago. The software is BridgeTab (by Jannersten Forlag).

Has anyone encountered a problem like this?

Is it possible that a plugin USB wifi adapter could take over from the in-built wifi and might work better than the in-built wifi.

 

[Ketchup]

What kind of router? How many devices are connected when you meet? Shouldn't be hard to find an app that will tell you what your signal strength is like.

Based on the fact that you have to turn your wifi off and back on so tha it will re-negotiate for an ip address, that does support the idea that the signal might be too weak at your location.

 

[think2]

The signal strength has been checked several times and it's very strong. There are wifi repeaters in the ceiling.
I don't know what kind of router. I will find out. On a typical night there's probably 40 to 50 devices - 160 to 200 people.

 

[ch33zw1z]

Need more info to help. One WAP for 50 devices?

 

[QuietDad]

40-50 active devices on a single WAP would be problematical in alot of situations

 

[think2]

I'll get some more information. A game lasts around six minutes at the end of which the score is sent to the server and some information on what other people did with that hand comes back, so most of the time there's very little happening.

 

[QuietDad]

Even if it sits idle most of the time,40-50 hands reporting at the same time....

 

[think2]

I found out there is a wifi transmitter in the ceiling so it has direct line of site to all the tablets. The transmitter is wired with CAT6 cable back to the base station. The ceiling is quite high - about twice as high as a normal ceiling. The wifi signal is strong and the transmitter can supposedly handle 100 connections.
Next time I see the problem I will check whether the wifi has actually disconnected. Is there any app I could install to try and get some data that might help work out what's happening?
I see on the internet that wifi problems are common and that turning the wifi off and on often fixes it - and it does in this case.

 

[ch33zw1z]

Provide more network topology specs:

What kind of "transmitter"? Make, model, revision, firmware, PoE? etc....anything you can about it.

What's the rest of the network look like?

 

[mxnerd]

Install WiFi analyzer app on the tablet and check.

https://play.google.com/store/apps/details?id=com.farproc.wifi.analyzer&hl=en_US

 

[VirtualLarry]

100 active wifi device client connections, to a single AP, is really kind of stretching things, I think.

 

[Ketchup]

The way I understand things, you are killing it, but only at bursts. I bet if you were all surfing the Internet it wouldn't be such a big deal. But that isn't going to work when you have 100 devices all trying to send data through one wireless device at one time, there is going to be delay, possibly even timeouts. I don't think there is going to be a solution any better than at least one more ceiling AP.

 

[MtnMan]

100 active wifi device client connections, to a single AP, is really kind of stretching things, I think.

If there is limited amount of data being transmitted, it still should work. Now if you exceed the number of DHCP address in the pool would be problematic. I think most routers default to 50 addresses in the DHCP pool.

 

[think2]

Provide more network topology specs:

What kind of "transmitter"? Make, model, revision, firmware, PoE? etc....anything you can about it.

What's the rest of the network look like?

The access point is Ubiquiti UniFi AP-AC-Pro
UniFi_AP-Pro_UG.pdf
looks like it can handle 250 clients. It can display the percentage of packets dropped.

Is there any software that can be installed on a tablet to show the number of dropped packets?

 

[ch33zw1z]

The access point is Ubiquiti UniFi AP-AC-Pro
UniFi_AP-Pro_UG.pdf
looks like it can handle 250 clients. It can display the percentage of packets dropped.

Is there any software that can be installed on a tablet to show the number of dropped packets?

Ok, so the two things that need to be checked for the WAP:

1. Firmware - ubnt rolls out updates pretty regularly
2. Controller software - ubnt WAP's are controlled by software, is it up to date?

Disclaimer: I've never used network traffic tools on a mobile device, here's what Google gave

https://developer.android.com/topic/performance/power/network/gather-data

If I were in your situation, I would also closely inspect the physical layer.

1. Is the cabling up to spec? If homemade network cables, are they terminated correctly (both jacks and heads)
2. Is power good at the Poe converter / wall jack? Nothing loose or worn down?

 

[mxnerd]

The total bandwidth of the AP is 2.4G 450Mbps + 5G 300Mbps, and you have 250 clients.

Could not find spec for Tab 3 A7-10, only some info about Tab 2 A7-10.

The only wifi spec can be found is it's a 802.11 bgn device so it's a 2.4G device. The 5G band of the AP is totally wasted.

https://www.lenovo.com/gb/en/tablet...ets-a-series/Lenovo-Tab-2-A7-10/p/ZZITZTAA002

450Mbps / 250 = 1.8Mbps. You definitely will get trouble when data is transmitted at the same time. And that figure is under perfect condition when there is no or little surrounding interference.

More APs will be required.

 

[think2]

Thanks. The tablets definitely cannot see a 5GHz channel - I took one home and checked. The AP is 1300 Mbps for 5 GHz. The most devices we've had connected so far is 45 and the most tables our clubrooms can hold would need 55 tablets.

We have two of these access points in the ceiling, one towards the west end and one towards the east. How will a tablet choose which access point to connect to - later today I will be able to check if the two access points come up with two different SSIDs.

Because of the way the licensing works, the tablets are each configured with a specific IP address to connect to or something - but I think that only affects at the application layer - I'm not sure exactly how this works.

For some reason, last Thursday night, almost every tablet in the place had problems getting feedback. The problem was about ten times worse than it normally is. A small number of the tablets are also rebooting unexpectedly and taking 5 to 10 minutes to restart instead of the usual one minute. We've turned off auto updates, they were previously on but for some reason there was no auto updating happening. Also for some weird reason the tablets have a mixture of firmware - ranging from S000020 to S000028.
Firmware

 

[think2]

Also, there's probably over a dozen stray 2.4 GHz wifi signals coming in to the building - 2.4 GHz seems to go a long way. How would we pick which channels to use for our access points? I believe they were changes to use non-overlapping channels a while ago and that helped.

 

[ch33zw1z]

https://community.ubnt.com/t5/UniFi-Wireless/roaming-wifi-between-3-x-UAP-AC-LR/td-p/1913122

Trying reading that, and googling for ubnt threads.

You'll need to use the controller software full time to get seamless roaming. The controller can be run on windows, Linux, either in a VM or a spare pc. You could also use a cloud key.

 

[JackMDS]

WIFI from it inception is based on hyperbolic statement rather than real functional Technological facts.

We all remember the fir few year that we wre promised 300 feet in close enviroment without explaining that what they mean in close enviroment (just one big room (220ft x 220ft and no interferiance like open office floor).

Similar is the conten cited in this thread. You to get good control for few hunderd clients you need at least 3 APs.

 

[mxnerd]

Seems Unifi AP has load balancing feature that you can turn on.

https://community.ubnt.com/t5/UniFi-Wireless/How-to-load-balance-with-Unifi-AP/td-p/1259634

It's a good idea to join Unifi forum.

They also have software called Unifi SDN Controller.

https://www.ui.com/download/unifi/default/default/unifi-sdn-controller-5929-windows

==

No idea about those firmwares. Would not touch it.

If you really want to update the firmware, better contact Lenovo tech support.

 

[think2]

Thanks. I didn't know what a "controller" is but it seems to be this
Controller V5 user guide
I'll read up about seamless roaming.

 

[ch33zw1z]

Cool, just keep in mind that the controller will need to be running all the time. The controller is the preferred method to upgrading the UAP's firmware as well. It's very functional software, ubnt does a great job IMO

 

[Muadib]

Cool, just keep in mind that the controller will need to be running all the time. The controller is the preferred method to upgrading the UAP's firmware as well. It's very functional software, ubnt does a great job IMO

Why??? I only run the controller when I want to change something, or update the firmware.

 

[ch33zw1z]

Why??? I only run the controller when I want to change something, or update the firmware.

Are you running multiple access points? And require seamless roaming?

I have a single UAP, two SSID's, I dont to run the controller software either.

It was my understanding that the controller software is required to provide seamless roaming for ubnt UAP's

Edit: it appears I may be wrong, properly configuring the UAP's can provide it, YMMV.

https://community.ubnt.com/t5/UniFi-Wireless/Roaming-without-UnifiController/td-p/2405613

Guest portal does, maybe that's what I was thinking of.