Optimal wifi parameters - a thread for lookup, experiences, comments

[Powerbooky]

Hi there,

since the question "why is my wifi so bad" or something related to wifi comes up ever so often, I'd like to open a thread about the most optimal wifi parameters for those access point hardware that allow more granular configuration.

I researched and experimented on several sites in different environments, including my own home/office network. Especially HomeKit and AirPlay took a lot of time to find the most optimal settings for less ideal RF conditions. Be aware that both consumer and enterprise grade wifi AP's both have factory defaults that never perfectly fit the environment where they are installed - except when you live outdoors with neighbours at least a mile away. 😉

Anyway... below the tables with custom radio settings for a Zyxel WAX650S used on different sites including my house. The similar settings are in use with UniFi AP's. So far in my own place it's running way smoother than the factory settings did, especially the custom multicast and RTS/CTS improved the network a lot for HomePod's.

Please feel free to contribute your experiences, alternate configurations and comments.

2.4GHz frequency band	Usually overcrowded, use it for IoT
Parameter	Setting	Why this setting?
Wifi type:	802.11ax (wifi6) or better preferred, but no less than 802.11n (wifi 4).	Avoid anything less than wifi 4 as they will interfere big with the newer devices. Get rid of 802.11b and 802.11g only devices.
Channel selection:	preferred EU: 1, 5, 9 or 13 (EU) preferred US: 1, 6 or 11 (US)	Many AP's do have automatic channel selection, but never work good. Use the Wireless Diagnostics (menu Window -> Scan) in macOS to see the best channel to be used on the spot you usually put your MacBook and set that manually.
Channel width:	20MHz	Avoid 40MHz or 80MHz as it overlaps the entire frequency spectrum spurring massive packet re-transmissions and collision noise in dense residential areas like apartments.
Multicast to Unicast:	Yes	Converts discovery packets into direct streams, stopping mDNS, Bonjour and HomeKit packet drops.
Minimum WLAN Rate Control	9Mbps or 12Mbps	Truncates slow management broadcast speeds. Frees massive airtime windows for far-away 802.11ax clients, instantly boosting stream stability. This improved my Tapo camera streams (C125) - I have a couple very far from the AP and recordings often used to be cut off prematurely.
A-MPDU Aggregation	Yes	Combines data blocks into unified payloads to squeeze maximum efficiency out of narrower 2.4G channels.
A-MSDU Aggregation	No	Prevents high packet retry rates. A single bit error inside a large MSDU drops the whole block over busy airwaves. The 2.4GHz band is inherently prone to background appliance noise (this includes DECT phones, bluetooth etc)
RTS/CTS Threshold	1518	Activates the RTS/CTS handshake for standard data packets. This forces aggressive neighboring APs to temporarily silence their radios, securing a clean, collision-free transit window for your Mac's data. This might lower the latency as well. Some wifi AP don't allow to manually adjust this. Often it is disabled or more intelligent AP adjusts this automatically (like UniFi).
DTIM	3	Apple recommended: client battery preservation by letting sleep states last through 3 beacon cycles.
Beacon Interval	100ms or 75ms	Standard is 100ms, but 75ms works better for far away clients when there are lots of other AP's from neighbours. Less sudden disconnects.

5GHz frequency band	Use mainly for MacBook's, AppleTV's, HomePod's
Parameter	Setting	Why?
Wifi type	802.11ax (wifi6) or better preferred, but no less than 802.11n (wifi 4).	Avoid anything less than wifi 4 as it will hog the newer devices.
Channel selection:	Any allowed channel	Many AP's do have automatic channel selection, but never work good. Use the Wireless Diagnostics (menu Window -> Scan) in macOS to see the best channel to be used on the spot you usually put your MacBook and set that manually.
Channel width:	40MHz or 80MHz	Avoid 160MHz. Very few devices actually support this, including Mac's. And it overlaps the entire frequency spectrum spurring massive packet re-transmissions and collision noise in dense residential areas like apartments. With 802.11ax or better, 40MHz can be good choice for anyone using wifi primarily for internet (200Mbps or less). Network TimeMachine backup's benefit more from 80MHz.
Multicast to Unicast:	Yes	Converts discovery packets into direct streams, stopping mDNS, Bonjour and HomeKit packet drops.
Minimum WLAN Rate Control	12Mbps	Truncates slow management broadcast speeds. Frees massive airtime windows for far-away 802.11ax clients, It also benefits AirPlay big time. Essential for AirPlay to stereo HomePods and/or multi-room playback.
A-MPDU Aggregation	Yes	Combines data blocks into unified payloads to squeeze maximum efficiency.
A-MSDU Aggregation	No	Prevents high packet retry rates. A single bit error inside a large MSDU drops the whole block over busy airwaves.
RTS/CTS Threshold	1518	Activates the RTS/CTS handshake for standard data packets. This forces aggressive neighboring APs to temporarily silence their radios, securing a clean, collision-free transit window for your Mac's data. It lowers the latency as well. Some wifi AP don't allow to manually adjust this. Often it is disabled or more intelligent AP adjusts this automatically (like UniFi).
DTIM	3	Apple recommended: client battery preservation by letting sleep states last through 3 beacon cycles.
Beacon Interval	100ms or 75ms	Standard is 100ms, but 75ms works better for far away clients when there are lots of other AP's from neighbours. It can avoid sudden disconnects due to other AP's broadcasting their own ID at the same time.

SSID specifics		Remarks
Enable U-APSD	Yes	Yes, except when using cheap IoT devices on this SSID. It can lower the battery drain on idle mobile devices
802.11k/v Assisted Roaming	No, when there are separate SSID's per frequency band Yes, when there's one SSID for all frequency bands or when using more than one AP for the same network.	There are more settings for roaming between AP's and frequency bands. The old style of "band steering" was simply cutting the connection on one frequency, forcing the client to search and reconnect, causing a noticeable short internet disconnect. If this option exists in your AP, disable it. Instead use 802.11k/v. The is also 802.11r, but doesn't always work with every device.

 

[drrich2]

since the question "why is my wifi so bad" or something related to wifi comes up ever so often, I'd like to open a thread about the most optimal wifi parameters for those access point hardware that allow more granular configuration.

Depending on how you define 'parameters,' what I'm about to share may or may not be what you had in mind. My grasp of networking is much less technical than yours appears to be.

1.) Don't put the router on the floor or inside a cabinet (my wife wanted it hidden; finally won that battle). It needs to be up, and be mindful metal and water can block wifi - so don't stick it right beside an aquarium. If you have a stand alone router, aim for a central location in your house.

2.) Router antennae broadcast signal outward most strongly perpendicular to the orientation of the antennae. So if you want strong horizontal coverage, situation your router's antennae vertically.

3.) Particularly for areas crowded with wifi clients and/or when dealing with high data transmission (e.g.: security cameras sending footage), use ethernet cable wherever you can. Just like taking traffic off the road releases congestion for what's left, free up your wifi.

4.) If possible, connect your mesh nodes with ethernet cable (turning then into wired access points), which in the case of wifi 6E or some wifi 7 systems may free up 6 GHz spectrum for other data traffic.

5.) Compare how many devices your router is rated for against how many you're using it to manage.

6.) Find out what spectrum your higher demand devices are connecting to. 6 GHz data speeds > 5 > 2.4 but distance and wall penetration are the inverse. If your wifi is bad in an area, do you need a mesh node or wired access point there?

7.) If it's an isolated area, like your kid's room, would a MoCA adapter or Powerline adapter in place of in-wall ethernet take care of it?

While the 'spirit' of my parameters is much different from the software settings configuration management you described, sometimes the best solution to a problem is something basic.