How do I know if a Dual band USB WiFi dongle will work on a Raspberry Pi running Linux? I know that Linux must have a driver that supports the wifi chipset used in the dongle. But with the number of WiFi dongles available how do you choose?
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1Have you thought about buying from a reputable supplier such as The Pi Hut, Pimoroni, Adafruit, Element 14, RS Components etc? You may need a powered usb hub though - Ralink RT5572 devices can suck power link nothing else (other than HDDs)! – May 22 '20 at 02:49
2 Answers
You can find a detailed list of supported RPi USB Wi-Fi Adapters.
If you have the USB/WiFi dongle available you can look at its valid interface combinations with iw list
. For example on a RPi 4B you will find:
--- snip ---
valid interface combinations:
* #{ managed } <= 1, #{ P2P-device } <= 1, #{ P2P-client, P2P-GO } <= 1,
total <= 3, #channels <= 2
* #{ managed } <= 1, #{ AP } <= 1, #{ P2P-client } <= 1, #{ P2P-device } <= 1,
total <= 4, #channels <= 1
--- snip ---
Here you will find how much channels are supported by a particular interface combination. For a more detailed discussion of this issue you can look at Can RPi4 run simultaneously on dual band (WiFi 2.4GHz / 5GHz)?.

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You can check on wiki.kernel.org for supported Drivers and his supported PHY modes : A/B/G/N/AC
802.11 B/G
work on2.4GHz Band
and802.11 A/AC
work on5Ghz Band
so it's Dual Band.802.11 N
have :single-band
2.4 GHz equipment (the oldest),dual-band
adapters (2.4 GHz or 5 GHz) ordual-radio
: 2.4 GHz and 5 GHz simultaneously.
I'm confuse with 802.11n
for my answer. But I think if 802.11n is in the supported PHY modes, 2.4GHz and 5GHz Bands should be supported by the driver.

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