Recommendations For IoT/Smarthome network optimization

Hello all,
I have been using Openwrt for a while, and i wanted to ask for some advice on optimization for Smart Home and IoT use.

I currently own 3 Archer A6 routers that are running OpenWRT 21.02.

One of the routers runs in router mode (Main router), and the other 2 run in access point mode. The Main router is connected directly to the ISP modem, and functions as router, firewall,dhcp, etc. The other 2 devices are wired to the main router, and are use them to extend my Wireless network.

All 3 routers run 4 Wireless SSIDs:
-1 2.4 GHz wireless for people to connect
-1 5 Ghz wireless for people to connect
-1 2.4 Ghz wireless to connect smart home devices
-1 5Ghz wireless to connect smart home devices

Each SSID traffic is associated with a specific VLAN, in order to keep Smart home traffic separated from user traffic. Additionally, i have looked at selecting the channels used by each SSID so they do not overlap. i do not have much interference from neighboring Wireless networks either.

The setup works fairly well, but i ran into some issues with a couple of remote controls that i built with old tablets, and control things like TVs, AC etc. The remotes send commands to a WiFi enabled IR Blaster that in turn send commands to devices that are not network capable.

For a while, i ran into this intermittent issue with the controls where pressing a button would not do anything, or the action would have a delay of several seconds. This translated into a really poor experience, since the user would not have a clear idea if the command really executed. Sometimes, the command would execute immediately, and sometimes it would take several seconds (even up to 10). Sometimes the user would press several buttons, and all the commands would execute at the same time, 10 seconds after.

This was driving me crazy. i troubleshooted the Smart home software, the tablet control and the IR blaster, and could not find any issues. Until i started capturing traffic and realized that the WiFi connected IR blaster was either not responding to the packets sent by the remote, or taking a long time to do so.

My network is not saturated at all (i have a 100+ MB connection, and i am usually not utilizing more than 10MB acording to the OpenWRT interface graphs). So for a long time i thought the problem was the IR blaster.

Then one day, i went to troubleshoot the issue further, and the control was behaving normally. this was extremely frustrating. At one point, my girlfriend returns home, and as he gets to the house, the remote starts malfunctioning again. My girlfriend has a number of Apple devices, including her phone.
Her phone was connecting to the "people" 2.4Ghz network, so on a hunch, i shut down the phone and the issue disappeared. Since the vast majority of my smart home network is 2.4, i moved all her devices to the 5Ghz network, and deleted the 2.4Ghz profile from the devices. The experience with the smart home network, and specifically, the remotes has improved greatly.

Now, since the "Smart home" and "People" 2.4 Ghz networks share the same radio, it makes sense that the phone could interfere with the smart home network. While the 5Ghz solution works for now, it is possible that i could have people in the house with devices that are not 5Ghz capable. For this reason, i would like to know if anyone has any experience with this kind of problems, and how do they handle them. Specifically:

-Does anyone know what could be running on the Apple devices that is so network-intrusive? i have my Android phone connected to the 2.4Ghz network, and have devices like streaming audio speakers, etc, that are not as invasive. It is specially strange that i do not see bandwidth saturation.

-Is there a way to give "air priority" to a specific client or even a specific SSID?

-Does anyone runs a scenario like this and has any recommendations? I have made sure that devices connect to the SSID with the best signal levels, and locked devices so they can only connect to that SSID. In general, the signal levels for both devices and APs are healthy. I cannot guarantee the same for mobile devices, but i have only 3 of those. everything that can be wired is wired.

-To investigate this further, does anyone now of any software that would help me map wifi "airtime" utilization per device?

-I do not have SQM enabled. I could enable it, but since the problem appears to be with local traffic, i was not sure it would be worth it. I also read SQM could be enabled on LAN interfaces but i am not sure if this would help at all, as it looks like it is design to to be used on the WAN interface?

I appreciate any help and tips, and i also want to thank everyone for producing such a great quality and feature ful product!

It's quite interesting, but your remote should really be utilizing VERY low bandwidth. I mean, I'd be shocked if it needed to send more than 10 packets a second and each one at most 1500 bytes that's 120kbps.

I would definitely make sure you turn off legacy rates, as if you've got devices using 1Mbps rates that'd be a potential issue for airtime. I think this is the default now, but if you have been keeping settings since earlier versions perhaps legacy rates are enabled.

Of course it's possible the remote control devices only utilize legacy rates, and that might be the issue as well!

But the real question is why does putting an Apple device on your network interfere with your remote control? Have you captured traffic on your interface and seen if maybe the Apple device is saturating the interface with something? I'm particularly thinking about multicast packets, which are sent by the AP at the lowest acceptable rate.

Do you have 802.11w Management Frame protection enabled by chance? I had similar issues sing the Roku remote from my iPhone when it was enabled and even when it was set to optional, disabling it was the only way the remote would work properly.

Hey @dlakelan:
The IR blaster is a Broadlink RM mini 3. It is spec'd as * WiFi802.11 b/g/n @ 2.4 GHz.
It should not be using legacy rates, but at the same, time, i have them disabled.

The remotes barely use any bandwidth at all. A udp packet every time you press a button and a very sporadic check with the "mothership" (Cloud).

Apple definitely makes use of multicast, specially if you have several devices. But i never associated this issue with the devices, because i never saw the network saturating, and also, the devices would be usually in different SSIDs, and that kind of masks the issue. But i will try to reproduce the problem and turn on the phone capturing traffic in the wireless network it is connected.

The comment you made about multicast being sent at the lowest acceptable rate is very interesting. I have a lot of tuya smart home devices that periodically send broadcast. i have been looking on how to disable this, but have not been able to so far. this are not the culprit of the issue, but they might very well be adding to it.


Hey @mike:
Management frame protection is disabled.

Maybe it could be Apples SmartHome app that thinks it should be in control of your home if she hasn’t turned it off.

But on the other hand Apple as standard assumes no one actually run a iPhone on something old low budget as 2,4GHz WiFi so my experience of Apples 2,4GHz is kind of always bad.

Bluetooth and USB 3.0 could interfere with 2.4 GHz wireless since they operate or emit RF at the same frequencies. Do you happen to use any of those?

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I definitely use Bluetooth. i have also some USB devices, but not close from where i am working with this.
I would be surprise that Bluetooth would cause so much trouble though. Maybe i should try and move to the lower channels of WiFi and see if it improves.