Frustrated by WIFI

[Simcfc73]

Evening all,

 

I've worked at my current school for a while and have never got a decent WIFI speed in school for some reason. Bit confused about why, I've read lots about channels and overlaps but cant figure it out.

 

We used to run a Ruckus system but I splashed out on new Unifi Pro gear, I've run the analysis tool so all the channels are set right but its not improved.

 

For example, our science block rarely always get top signal as I ran the Unifi signal tester and it was all green as good but the download speeds rarely hit more than 600kb.

 

I'm running PDQ deploy now with no one on the WIFI and its doing the same in a different block. When I look at UNIFI stats its showing as 55dBm and speed of 144Mbps.

 

I actually bought new laptops too for science with AC chips in but the speed is still awful, its not the network as a desktop on the same switch is flying.

 

The switch isn't showing any errors either.

 

Anyone got any tips I can try, its very weird.[TABLE=class: ubntTable ubntTable--secondary ubntTable--flush]

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[Steve21]

144.4 is the cap on 20MHz range (2x2 MIMO)

 

You sure it’s setup right config wise? It shouldn’t be running at that unless it’s setup to auto adjust down to 2.4ghz when it detects conflicting networks/APs etc (or didn’t you disable those?)

 

Can you force it to stay at 40+ and retest it?

 

Steve

[p858snake]

How is your wireless interfaceing the rest of the wired network? could it be bottle necking in that aspect?

 

What type of buildings are the access points in? how many access points?

[XiJ]

You haven’t got any of the unifi’s on a wireless uplink? This happened in one of our schools and the network slowed to a crawl. Seemed obvious when I discovered it but left me confused for a while.

[Simcfc73]

144.4 is the cap on 20MHz range (2x2 MIMO)

 

You sure it’s setup right config wise? It shouldn’t be running at that unless it’s setup to auto adjust down to 2.4ghz when it detects conflicting networks/APs etc (or didn’t you disable those?)

 

Can you force it to stay at 40+ and retest it?

 

Steve

 

I've set the APs to HT40 with the power lowered to medium (as suggested on a different forum), I couldn't find a setting on the client to set this... other than to force it to use 5Ghz.

 

The uplinks plugged into the same switch as a desktop client which is getting 50+ mbps.

 

I've run lanspeedtest too which hangs for ages on the laptop but is instant on the desktop.

 

The room I was testing last night is a normal old brick building with the AP less than 20 metres away with one wall in between, I've run the WIFI analyser and its hitting good all the time.

[AlanD]

So many questions....but let’s be clear with a wall and distance of 20m you are NOT going to get any of the benefits of ac channels and you may struggle to get anything reasonable from 5ghz spectrum, so you will be stuck with 20mhz channel on 2.4ghz band...the same as you might get with historic wifi kit. Add to this the fact that many ac chip sets in a laptop are single stream only and you are lucky if you are getting 144mb/s.

 

The lure of ghz plus wifi speeds quoted by access point suppliers comes with need to understand how they might be obtained. Yes, if you have an isolated barn, and can use a single AP with single client, you can have an 80Mhz, or even 160Mhz channel, with 3 or 4 streams given a suitable client chipset. Then you might get 1gb/s at distances of a couple of metres. But....if you want lots of clients...and you are going to have neighbouring APs which limit your channel width wifi is Going to struggle...particularly if you want to do something more than browsing. Logging on AD to a server with user profiles etc and class sets of laptops is going to be tediously slow. Don’t let ant wifi seller tell otherwise.

 

The AP will need to be in classroom for best results. An AP out in the corridor with signal through a wall seriously starts to limit what can be delivered.

[chazzy2501]

Dude for a sanity check, put all of the devices and settings in auto. I have gone from N to 1700AC and the download speed of my laptops still only hits 8MB nearly 50% faster than the old N setup. So many environmental factors go into getting better wifi it'll hurt your brain.

 

EDIT: 2x2 mimo 144 means 72mb up 72mb down. (and we know you never get 72mb) a 3x3 mimo will switch the ratio 1x2 or 2x1 depending on what demands more but you can see how the speeds are optimistic. With overheads and interference distance and contention the throughput can be less than stellar.

Edited October 14, 2019 by chazzy2501

[PotNoodleTech]

Do you have one AP per classroom? That made by far the biggest difference here rather than individual models of AP (and i did do a lot of AP testing cisco v unifi). Going through walls is simply a big no no nowadays.

 

Some of the walls here are a meter thick - we didn't even realise until we knocked one out to put a glass window in and was like.....er this is gonna need to be a thick pane of glass!

[chazzy2501]

wifi has to travel in straight lines so image a cross section of your wall, it may only be a foot thick but at a 45 degree angle that wall is now 3ft thick. (wifi can bounce and is a wave which is why 5ghz is nearly doubly affected by walls)

[wright-fi]

I've got quite a bit of experience with Wi-Fi (I work at a wireless focused company and hold CWNA, CWSP and CWDP professional wireless qualifications), so I'm hoping I can help here. I have a few questions regarding your current setup if I may.

 

So with your current system you're getting a dismal 600kbps, how does that compare with your previous Ruckus system?

What channel widths are you using?

What power setting are you using (auto or a specific value)?

How many AP do you have in total?

Are you meshing?

 

I'd also like to understand a little more about your environment.

 

Can you tell me more about the walls in your school, are they thick and brick, so they have soundproofing?

And how many classrooms do you have?

Are you using a 1 AP per classroom approach?

Are you need an Airport?

Have you or anyone else completed a spectrum analysis of your school?

[AlanD]

OK - so now I hear some of the right questions being asked. There is some difference between what you can get out of expensive (annual charges) APs and cheaper Unify ones - but all my experiments with a class set of laptops required a stop watch to measure the difference. One AP per classroom isnt always the best solution - sometimes trimming back on the odd AP will allow you to use wider channels without overlap, but if you are serious about using class sets of laptops with AD logins - you probably need to start with that in mind. Multiple streams MIMO, and MU-MIMO as good as they might seem on paper need a really strong signal to noise ratio (so I wouldn't be backing off any power on 5GHz band - although I might turn off the 2.4GHz radios on every other AP especially if that gave me 3 non overlapping APs). Even with the top APs, distant signals on the weather radar frequencies are often interpreted as being weather radar and the APs slowly one by one stop using those frequencies - which is annoying - even if you are not close to an airport.

 

And keep in mind that wireless is a single collision domain...and with 20 or more laptops its not a case of take the speed you had with a single laptop and divide by 20....because you will be lucky if you get half of that.

 

Good classroom management helps. Don't get laptops out...and step by step get students to switch on and login. That will take 20 minutes (possibly longer as some will get fed up waiting and decide to reboot their machines). Get them to do this as soon as they start arriving through the door so that by the time the last student has arrived - there is only that laptop to login. Better still if its one to one and they can login once at the start of the day and carry their laptop with them.

 

In the real world - you are unlikely to see a significant difference between using "N" APs with 5Ghz than using "AC" with 5GHz....because the chances are in a dense deployment you are limited to 40Mhz channels - and no improvement at all if your laptops only have 2.4GHz chip sets. Yes - if you have 2x2 MU-MIMO chips sets in your laptops then with an AP in that room - it should make a difference. But with a wall and gap of 20 m - no chance.

[Simcfc73]

Thanks for all the replies.

 

I suppose the frustrating thing is when i am in on my own in the holidays. I can use just one machine sitting right next to the AP and its still pants.

 

I'll do a bit of tweaking in the holidays and input some of the suggestions offered.

[PotNoodleTech]

I suppose the frustrating thing is when i am in on my own in the holidays. I can use just one machine sitting right next to the AP and its still pants.

 

Interesting! My rule of thumb is - if it's still slow in the holidays with no kids and no teachers - then there's something seriously wrong with it or it's setup!

[mavhc]

Step 1, turn off all but 1 AP. Speed test with that, in the same room, not super close, say 2m at least away. Compare with LAN speed. What speeds do you get? iperf is the speed test I normally use.

 

Use -i 1 to report every second, -t 1000 to run for 1000 seconds

[Primus]

Interesting! My rule of thumb is - if it's still slow in the holidays with no kids and no teachers - then there's something seriously wrong with it or it's setup!

 

This - something is seriously wrong here. You're going to need to go back to basics on your config to get to the bottom of this.

 

For context we have an AP in every classroom and even with plenty of WiFi devices connecting and roaming about interfering I can reliably speed test at over 150Mb at any point of time in any given location.

[Michael]

Two things come to mind -

 

Have you used a WiFi Analyzer? I use one on my Smartphone and it's useful to see what's in the immediate area.

 

Is there a nearby Community WiFi? I've seen such solutions which literally flood the 2.4GHz band and could possibly explain why you're seeing poor speeds. The 5GHz band in my experience is generally pretty clear still, so I'd expect the Unifi APs to automatically shift compatible devices onto this band.

[chazzy2501]

Unplug an AP in question and plug your laptop into the ethernet it is using then swap some files for speed testing (test ping, and DNS, dhcp as well). At least eliminate an issue with the wired connection first.