Nebula [AP] - Best Practice Optimizing 2.4GHz & 5GHz Wireless Network

This article aims to provide a comprehensive guide on optimizing your Access Point WiFi setup in Nebula, ensuring a seamless wireless experience while minimizing interruptions, internet disconnections, and slow connectivity issues. 

This article explains: Roaming, Smart Steering, Interference (Channel Utilization), Speed issues, Channel Width, Output power, Band Select, WLAN Rate Control Setting, Connectivity issues, Dynamic Channel Selection, Intra-BSS traffic blocking, Layer 2 isolation,  Load Balancing, Chromecast not connecting.

Disclaimer! This is an article that explains the best practice to increase performance for general WiFi environments. These suggestions might not be applicable to your specific environment if it differs from the "normal" conditions of a WiFi environment. Most of these parameters will therefore be a trial-and-error practice to find the optimal parameters for your environment. 

For signal quality issues and a more complicated setup, check out this article:

For Nebula devices: Nebula [AP] - Best Practice Optimizing 2.4GHz & 5GHz Wireless Network
For Stand-Alone devices: Wireless [WiFi] - Best Optimizing Practice 2.4GHz & 5GHz Network

 

Roaming

If you are experiencing that your connection at some points "freezes", if you have a hard time getting a good signal strength even though you are connected near to the Access Point (AP),  or if clients start off with a good connection, but after going to the next AP, the connection is unstable before it is lost. These symptoms, generally speaking, are what we refer to as Roaming Issues.

Note that a smooth roaming experience is mostly because of a good deployment and not the setting itself.  However, the configuration might help with the roaming experience. A client should be roaming when the signal strength goes below -75 dBm and the signal of a Wifi client should ideally be higher than -65 dBm wherever the clients move in the WiFi environment.

Smart Steering

Smart Steering is used when you have more than 1 AP. This prevents "Sticky clients", which is a term used for WiFi clients that are connected to an AP (AP1), and when they move to the next AP (AP2), they do not connect to the AP2, even though the signal is better on AP2. This is because they still have a signal on AP1 (even though it's bad), the client determines that the signal is enough for an internet connection.

Here we can enable Smart Steering, which forwards a client to the next available AP when the signal reaches a certain "low" level. This ensures that you have the best possible signal wherever you are in the environment. If the client gets too low a signal, and there is no AP around that can give a better signal, they will kick the client out of the WiFi completely. The client needs to go closer to the AP again to be able to connect.

Best Practice values (On both 2,4GHz & 5GHz)

Optimization Aggressiveness (Start setting this value to normal)

• High - the AP forwards clients more aggressively to the next AP if the client is not having a good signal
• Normal - When the signal reaches below -75 dBm, forward the client to the next AP
• Low - the AP forwards clients less aggressively to the next AP if the client is not having a good signal

Disassociate Station Threshold: -88 dBm

When the signal reaches below -88 dBm, kick the client out of the WiFi and don't let it be able to connect until the signal gets better than -88 dBm

• How to configure? 

Go to Site-wide -> Configure -> Access points -> Radio settings

Roaming protocols 

•  802.11r - IEEE 802.11r is a standard for fast roaming in a wireless network, also referred to as Fast BSS Transition (or Fast Roaming). Without support for 802.11r, this would require the client to re-authenticate causing issues for users (source). If you're having RADIUS / Active Directory authentication, this should be enabled. 
• Best Practice values (On both 2,4GHz & 5GHz)

Disable 802.11r, if you're not using 802.11x (RADIUS or AD authentication) on WiFi

• 802.11k/v - The 802.11k standard helps devices search quickly for nearby APs that are available as roaming targets by creating an optimized list of channels. When the signal strength of the current AP weakens, your device will scan for target APs from this list (source). However, the protocol isn't supported on all devices, which can lead to problems.
• The 802.11v standard can direct devices to roam and can accept and respond to these Basic Service Set (BSS) Transition Management frames, leading to improved WLAN quality when connected to a network that supports 802.11v (source). However, the protocol isn't supported on all devices, which can lead to problems. 

Best Practice values (On both 2,4GHz & 5GHz)

Disable 802.11k/v, if you have roaming issues. This might be because of unsupported devices, or other issues related to the protocol.

• How to configure?

Go to Site-wide -> Configure -> Access points -> SSID advanced settings

Interference (Channel Utilization)

• What is interference?

WiFi Interference is a problem that occurs when two signals in the same frequency is used near each other. Think of co-channel interference (WiFi interference) as waves in the ocean when it comes from two different directions, instead of being "smooth" waves traveling, they will bump into each other and cause "collisions". In our devices, the interference level is labeled as "channel utilization".

• When does interference occur? 

Some cases might include equipment (and/or other WiFi) nearby

If you have a microwave, or any other equipment that sends out signals on the same frequency, this will cause interference. It could also be that you are in an office building where there are a lot of companies that has their own WiFi. Their WiFi environment will reach your WiFi environment, and it will create a collision.

When you have your two access points too close to each other

If you have two access points near each other that are operating on the same channel, it will cause a collision

When you install the WiFi on the floor above, and the signal "spills" onto the floor under

• How to check your interference level

Go to Site-wide -> Devices -> Access points

Click on the "document/list" icon and select the channel interference on 2,4GHz & 5GHz (6GHz)

 

Speed issues

• Channel Width

Whenever you experience a slow WiFi, this could be because of interference. To reduce the interference level (channel utilization), you can turn down the channel width. This will decrease the WiFi throughput overall, but if you have high interference levels, you will increase the throughput (speed). Channel width operates on a frequency spectrum from 20 MHz up to 160 MHz channels, higher channel width means increased maximum speeds, but also increased risk of interference.

• Best Practice values (On both 2,4GHz & 5GHz)

If you're experiencing inconsistent speeds, WiFi disconnections, etc., turn down the channel width to 20 MHz on both 2,4 GHz and 5 GHz.

• How to configure Channel Width?

Go to Site-wide -> Configure -> Access points -> Radio settings

• Output power

A common problem will be that in order to avoid interference, you turn down the output power of the APs. However, this will create "grey areas" in your WiFi environment where there is no WiFi connection.

However, sometimes it is necessary to turn down the output power, because of an incorrect WiFi installation. 

• Best Practice values (On both 2,4GHz & 5GHz)

Start with decreasing the output power with 3-5 dBm to the radio that has high interference (e.g. 2,4GHz) to see if this helps the interference level (See section 2.1.2 How to check your interference level). If channel utilization goes down, try to decrease it again with 2 dBm. If channel utilization stays the same, there could be other issues such as "DCS" settings (see 2.2.1 Dynamic Channel Selection (DCS) Settings).

• How to configure Output Power

Go to Site-wide -> Configure -> Access points -> Radio settings

• Band Select

Band select is a function that forces clients to connect to the 5GHz band. This is because 5GHz, generally has lower interference levels, and it's also faster. The access point will try to force the clients to connect to the 5 GHz network 3 times before it will accept the client to connect to the 2,4GHz. 

• Best Practice Values

If you're having a high interference level (channel utilization) on 2,4GHz but good channel utilization on 5GHz, Band Select might be a good option. However, some devices is not supporting band selection and it might cause more problems in your network environment. Therefore, the best practice is to leave this feature disabled.

• How to Configure Band Select

Go to Site-wide -> Configure -> Access points -> SSID advanced settings

WLAN Rate Control Setting

WLAN Rate Control is the feature to let users set up the basic transmission rate of AP.

Since the management frame, broadcast, and multicast packets use the basic rate to transmit, this would impact the network performance due to the low speed.

If the network environment is well deployed (such as the signal of clients around -50 dBm to -60 dBm), configuring the higher basic rate has benefits to the network performance which include reduction of management overhead, better airtime utilization, and enhanced throughput, especially in high-AP-density scenarios.

In other words, the WLAN rate control feature is used to modify the basic transmission rate of the AP, and the rate limit feature is used to limit the transmit rate of clients connected to it (source).

• Best Practice Values

If you have interference issues, WLAN rate control will probably not help you with this. However, if you have a dense WiFi environment (many clients connected to the APs) and you want to increase throughput (speed) in your WiFi environment, you might change the WLAN rate control value to 6 Mbit/s for 2,4 GHz and 11 Mbit/s for 5Ghz (and 6GHz). However, increasing the WLAN rate control might create outages and disconnections for your WiFi clients if you .

•  How to configure WLAN rate control

Go to Site-wide -> Configure -> Access points -> Radio settings: WLAN Rate Control Setting

Drag the line to change the values

Connectivity issues

• Dynamic Channel Selection (DCS) Settings

Dynamic Channel Selection (DCS) is among the most important wireless communication elements in dynamically changing electromagnetic environments wherein, a user can experience improved communication quality by choosing a better channel (source). In lay terms, this element is dynamically choosing the proper channel to use in the environment, by scanning the environment for the least occupied channels in that area. 

• Best Practice values (On both 2,4GHz & 5GHz)

If you're having problems with interference, make sure that you have enabled DCS and that it is scheduled every night. If it's scheduled in the middle of the day, this "channel selection" will be happening during office hours, which will disrupt and disconnect all users at that time of channel selection. Also, if the DCS time interval is set, you have no control over the time when the DCS is happening, thus, it can disrupt the WiFi in the middle of the day. 

The best practice for DCS is therefore to enable DCS schedule to the middle of the night, disable DCS client aware, disable Avoid 5F DFS channel (if there's no airport/seaport/military base/weather stations, etc. nearby the WiFi environment) and set 2.4Ghz channel deployment to "All available channels" - if you're having high interference level (channel utilization).

• Intra-BSS traffic blocking - Cannot reach devices in my network

Intra-BSS Traffic Blocking makes sure that the wireless clients cannot talk to each other and is an important part of the Layer 2 isolation. When this is enabled, the device (e.g. Chromecast) won't be able to talk to the mobile phone, laptop or any other clients in the network which will prevent the connection to be established. Best practice for Intra-BSS Traffic Blocking is to only enable this for Guest WiFi's that is for clients that you don't trust.

• How to disable Intra-BSS Traffic Blocking?

Make sure SSID is enabled and Guest Network is disabled

Go to Site-wide -> Configure -> WiFi SSID settings

Make sure that Intra-BSS traffic blocking and Layer 2 isolation are disabled

Go to Site-wide -> Configure -> Access points -> SSID advanced settings:

• Unsecure network - WPA2/WPA3 standard

If you're having problems with devices not trusting WiFi, you might want to increase the WPA standard to WPA3, or change the password of a WPA2 encryption to a strong password. 

A strong password consists of:

at least 12 lengths of the password, at least one upper case letter, at least one lower case letter, at least one number, at least one special character

•  Load Balancing

If you're having users kicked out from the WiFi, when there's a little higher load than usual. It could be useful to configure Load Balancing to balance out the clients when the load gets too high. 

Utilize the Load Balancing function to control the number of devices connected.

• Choose “Enable by client device number mode".
• Input 2.4G/5G Maximum client devices number. For a more stable and efficient WiFi connection, we recommend limiting the number of connected wireless clients to 15-20 per AP at the same time. 
• Toggle “Disassociate client device when overloaded”. When the station number is greater than the max station number, AP disassociates clients with the longest idle time and the poorest signal strength. 

Go to Site-wide -> Configure -> Access points -> AP & port settings