Large(?) IoT WiFi network performance: suggestions!

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mspinolo

New Around Here
Hi All,

I have a large (at least according to my router brand support) 2.4G WiFi network (40-ish clients) spread over a medium size (200 m^2) house (with some thick walls).
Wifi network is provided by Synology 2600AC router plus 2 MR2200AC router in mesh setup: backhaul connection is using 1Gbit ethernet line.

I ran a Netspot site survey except having a not great signal-to-interference level (which I believe is due to the number of clients?) all seems fine.
Survey available here

Now issue I have is my 2.4G network is not really stable, according to Synology support this is due to some devices (5) with poor signal quality.
Synology is reporting a rate from 0 to 100 and these 5 clients have a link quality of 23-26-26-32-30: they are all IoT device (SolarEdge solar inverter, 3 Lifx bulbs, 1 shelly switch) for which I expect a low level of traffic.

Now I can boost the signal of 3 of them (plus other 2 not included in the 5 above with a link quality of 36-38) by adding a wifi repeater, but I am unsure this is the right thing to do: can anyone share suggestion or suggest a way to assess which is the best setup? (with or without wifi repeater).

I can use Wireshark although not being really expert in analyzing data, so suggestion is welcome.

On the other hand I am not sure if issue is with my current gear as, although poor level of connection, I would expect that, given the low number of clients and relatively low traffic, I shouldn't experience issue. I considered different times to entirely move to Ubiquiti Unifi gear, so also suggestion in this respect would be appreciated!
 

thiggins

Mr. Easy
Staff member
IoT devices can be a challenge. They typically have old, crappy radios to start with. Then there's the fact that they are black boxes; you can't see anything about the quality of the signal level they are experiencing.

I would not start by adding more APs. Look for patterns in the poor performance. Is it device type? manufacturer? devices connected to a specific mesh node? time of day?

I assume your three APs are set to different channels using 1, 6, 11 and using 20 MHz bandwidth mode.

At any rate, since your "mesh" APs are connected via Ethernet backhaul, go ahead and try a repeater.
 

mspinolo

New Around Here
Hi Tim,

thanks for that.
Some IoT are actually open source firmware (EspHome) so I can inspect what they are doing: signal level is around -80dB so not great altough not a disaster.

Synology, once in mesh configuration, can't be assigned with different channels :rolleyes:, so I have all @ channel 6 (which is not used by neighbours) @ 20Mhz.
Also looks like Synology has some issue with MacOS: every time I boot my Mac some devices quickly disconnect for few seconds.

Other issue I see with wireshark is that multicast packets are higher than I would like (still not high though, like 70 packets in 10s max): this is something releated to ESPhome IoT clients which act as "servers" to my IoT hub. Not ideal should be corrected in a future release.

So do you suggest to carry on with the repeater?
 

thiggins

Mr. Easy
Staff member
You don't need the MR2200AC to operate in mesh; you have Ethernet backhaul. If you can, run them as access points, then you should be able to assign channels as needed. If all three APs are on the same channel and you have significant overlap, then co-channel interference will be high. That could cause devices to ping-pong between nodes.

I wouldn't worry about multicast traffic.; there's not much you can do about it. Instead, you might want to look for retries (wl.fc.retry), disassociation (wlan.fc.type_subtype=10) and deauths (wlan.fc.type_subtype=12). Events near disassociation and deauths in particular could tell you something about why devices are losing connection.
 

mspinolo

New Around Here
You don't need the MR2200AC to operate in mesh; you have Ethernet backhaul. If you can, run them as access points, then you should be able to assign channels as needed. If all three APs are on the same channel and you have significant overlap, then co-channel interference will be high. That could cause devices to ping-pong between nodes.

I wouldn't worry about multicast traffic.; there's not much you can do about it. Instead, you might want to look for retries (wl.fc.retry), disassociation (wlan.fc.type_subtype=10) and deauths (wlan.fc.type_subtype=12). Events near disassociation and deauths in particular could tell you something about why devices are losing connection.
These are all great suggestions!
I will have a look into it, thank you really much!
 

mspinolo

New Around Here
So I am trying to catch something with wire shark but I think I am hitting the limit of what I am able to do with this software.

I captured 4h but I saw no packets similar to what you suggested.
Then during the night (unluckily I was not capturing) 2 devices disconnected and didn’t reconnect (rebooting the clients and they reconnected).

still in mesh config, I really think I need to switch to AP mode (?)
 

thiggins

Mr. Easy
Staff member
Are you sniffing with a Wi-Fi adapter that supports monitor mode? That's the only way you'll see 802.11 packets. You'll likely have to be running a Linux system, too.
 

mspinolo

New Around Here
Are you sniffing with a Wi-Fi adapter that supports monitor mode? That's the only way you'll see 802.11 packets. You'll likely have to be running a Linux system, too.
Hi,

I am using an RPI3 running linux with Tshark wired to the network: I was wondering it would be fine, isn't it?
Eventually I can setup an RPI0 and sniffing via a monitor-mode enabled dongle: I presume I need to do it in different locations, is that correct? (maybe near devices getting disconnected?)
 

coxhaus

Part of the Furniture
Having 2 APs will distribute the load better and should keep the signal stronger using 2 APs vs 1 router providing the APs are spread apart.
 

mspinolo

New Around Here
Having 2 APs will distribute the load better and should keep the signal stronger using 2 APs vs 1 router providing the APs are spread apart.
you mean having 2 APs + 1 wireless router is better than 1 wireless router + 2 mesh satellite?
 

thiggins

Mr. Easy
Staff member
If you seeing any 802.11 packets in your captures your setup is fine. You should sniff near the problem devices.
 

coxhaus

Part of the Furniture
I don't run a wireless router. I just run 2 Cisco WAP581 wireless APs. I was thinking 2 wireless devices. Wireless mesh is not my cup of tea. I still believe in ethernet back haul for wireless APs. Cisco publishes they support 200 connected devices and 64 active devices per radio per AP. Both 2.4GHz and 5GHz radios support 64 which is a total for 128 active users per AP.

Consumer wireless does not publish how many devices they support per radio per device. Even if they did they probably would stretch the truth. So you need enough hardware to cover your wireless needs.
 

Trip

Very Senior Member
Aside from hard-wiring your MR2200ac units and optimizing channel usage, you may also want to play with airtime fairness (ATF), which I believe is supported. ATF limits per-device downlink airtime so that no single devices hogs too much radio time for too long -- at least that's the way it's supposed to work. You may find it better to leave it off, but it's at least worth a shot. I can't find a reference to where the setting is specifically located in the Synology firmware, but I would look in the advance wireless settings area for starters...
 

mspinolo

New Around Here
Hi, thank for all your tips.

I moved to a "wired AP config" and set them to 1-6-11 channels.
I can't see any ATF setting inside synology unluckily :(

Do you guys know if there is a free alternative to NetSpot to carry out a site survey?
 

sfx2000

Part of the Furniture
Looking at the NetSpot report - you likely have too many AP's.

Try taking one off-line - and as mentioned by @thiggins - if you have gigabit backhaul, you don't need the mesh.

@Trip - on the Syno 2600 - ATF is always enabled, it's part of the Qualcomm BSP, cannot disable it

NetSpot is pretty good for site surveys.

Tips on the RT2600 - might consider disabling the "smart connect" feature and configure each radio separately - can leave on multicast translation.

For 2.4G - leave the radio in 20MHz only, the ESP's on your IOT devices will appreciate this.
 

mspinolo

New Around Here
Looking at the NetSpot report - you likely have too many AP's.

Try taking one off-line - and as mentioned by @thiggins - if you have gigabit backhaul, you don't need the mesh.

@Trip - on the Syno 2600 - ATF is always enabled, it's part of the Qualcomm BSP, cannot disable it

NetSpot is pretty good for site surveys.

Tips on the RT2600 - might consider disabling the "smart connect" feature and configure each radio separately - can leave on multicast translation.

For 2.4G - leave the radio in 20MHz only, the ESP's on your IOT devices will appreciate this.
hi there,

thanks for you hints!
So all this has already been set as you suggested.
Also I found adding a feature (can’t remember the name now but had to do with improving battery life of mobile devices) made worse IoT stuff connection.

I have DTIM set to 3 on 2.4G: is it suggested to reduce it?

In terms of AP number: Netspot is in fact suggesting I have too many APs, in mesh mode, as it was before, it is not possible to change WiFi power(always high)while it is now they are configured in AP mode.

So I should reduce it on some AP and make some test: unluckily netspot trial license expired.
Are you guys aware of any alternative for a site survey?
 

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