Troubleshooting Tip: 6 GHz channel detection on FortiAP 443K/441K

Description

This article describes steps to troubleshoot 6 GHz channel issue on FortiAP443K when the channel does not appear on the FortiGate GUI and CLI.

Scope

FortiGate, FortiAP.

Solution

In this AP model, the channel detection happens through the GPS signal.

Make sure FortiGate country code is set correctly, as this FortiAP model uses GPS positioning to get the coordinates, which is required for 6 GHz channel selection. For example, if the FortiGate country code is set for Canada and if the FortiGate and Access Points are deployed in the US, this will cause the wrong calculation of coordinates.

Power mode specification:

The regulatory power mode specifications for the 6 GHz Wi-Fi spectrum (Wi-Fi 6E and Wi-Fi 7) under the Automated Frequency Coordination (AFC) framework are strictly defined by regulatory bodies like the FCC.

Without AFC, 6 GHz routers are locked into a lower-range, indoor-only mode. Activating Standard Power (SP) Mode via AFC increases the allowable transmit power by up to 400%, allowing for outdoor deployment and significantly better indoor range.

Automated Frequency Coordination (AFC) is a cloud-based system that manages 6 GHz Wi-Fi spectrum usage, enabling Wi-Fi 6E/7 access points to operate at higher 'standard power' levels without interfering with existing licensed users (e.g., satellite, microwave links). It is mandatory for outdoor, high-power 6 GHz FortiAPs.

Currently, the 6 GHz frequency bands primarily operate in three modes:

• LPI (Low Power Indoor).

• SP (Standard Power).

• VLP (Very Low Power).

FortiAP443K only allows the use of 6GHz SP power mode, which needs AFC. Enabling an Automated Frequency Coordination (AFC) system unlocks Standard Power (SP) Mode.

It raises the maximum transmission limit from 1 Watt (30 dBm) up to 4 Watts (36 dBm). This grants up to eight times the signal strength on wide 160 MHz channels, allowing the 6 GHz signal to punch through walls, eliminate dead zones, and match the range of 5 GHz networks.

SP mode is a superior mode, offering higher transmit power and wider coverage. However, it requires the dynamic allocation of RF resources and necessitates that the FortiAP provide its own geographic coordinates; consequently, for operation on FortiAP441K or FortiAP443K, GPS capability is required.

In situations where the SP mode requirements cannot be met, the FCC also permits FortiAP’s to operate in LPI mode, a low-power mode characterized by reduced transmit power and limited coverage area, provided they are utilized exclusively in indoor environments and equipped with integrated Wi-Fi antennas. The FortiAP441K meets these criteria and is therefore capable of operating in LPI mode. But FortiAP443K does not.

FortiAP will connect to an AFC server with its location information, and then the server will respond with the available channel list. Then FortiAP could work according to the info.

441K is an indoor FortiAP; it can work in LPI (low power indoor) mode.

The FortiAP443K features a detachable Wi-Fi antenna; in accordance with FCC standards, it cannot operate in LPI mode and must instead operate in SP mode. That is, it is required to obtain its operating channel via AFC.

The antennas fall into two categories: WiFi antennas (grouped in sets of three or four) and GPS signal antennas (single units). The term 'detachable antennas' refers specifically to the WiFi antennas; this feature impacts AFC.

The FortiAP441K is fully capable of receiving a GPS signal without an external antenna connected. However, the FortiAP443K is entirely dependent on external Wi-Fi antennas to function.

Among these, VLP is available only in select countries and is not supported in the United States.

Both the FortiAP441K and Forti443K support SP mode; however, per FCC regulations, the RF resources required for SP mode must be dynamically requested. When requesting these RF resources, location information regarding the FortiAP's physical site must be provided. Without GPS, FortiAP441K can work in LPI mode, but FortiAP443K cannot. The FortiAP443K supports SP mode only and requires GPS.

On the 441K and 443K models, this location information is derived from GPS signals; consequently, these devices are unable to provide service in locations where GPS coverage is unavailable.

If a GPS signal is not available, the static positions need to be configured by entering the longitude and latitude values of the FortiAP.  LOWI is only available on version 8.0 for both FortiAP and FortiOS.

User Input Position (Static LOWI).

There is a way to manually configure a static location if the GPS signal is not available. To manually set a static location for a FortiAP, a feature referred to as 'static LOWI', use the following commands. Note that the location options will only appear after static-lowi-enable is active. Make sure to channel width to 160 or 320 MHz in the FortiAP profile.

configure wireless-controller wtp
edit <FortiAP-serial-number>
set static-lowi-enable enable
set static-lowi-lat <latitude>
set static-lowi-lon <longitude>
set static-lowi-alt <altitude>
set static-lowi-lat-err <latitude_error>
set static-lowi-lon-err <longitude_error>
set static-lowi-alt-err <altitude_error>
end

Note: Disabling this feature will remove the static position data

Verification:

Check the current positioning status and data from either the FortiGate or the FortiAP itself.

On FortiGate:

Use the following command to view the currently used position data for a specific FortiAP.

The lowi-pos-type field will indicate the source of the data (static, GPS, or LOWI).

On FortiAP:

Use the following commands to check the LOWI and 802.11mc status directly from the FortiAP's command line:

Check LOWI status:

> wcfg | grep lowi

Check 802.11 mc Mode:

> wcfg | grep 802.11mc

This shows the operational mode (e.g., auto).

Check Radio 802.11mc Capability:

> FortiAP-441K# rcfg | grep 802.11mc

This indicates whether 802.11mc is enabled or disabled on each radio

A few more debug commands are available at the command line of FortiAP:

> cw_diag -c afc dump afc_request.txt
> cw_diag -c afc dump afc_request.txt
> cw_diag -c afc dump afc_response.txt
> Debug commands for AFC:
> cw_diag -c afc status
> cw_diag -c afc decrypt-location
> cw_diag debug afc

AFC logs can be seen on the console.