wifi

Working with multiple WiFi interfaces on a Raspberry Pi

Sometimes I like to connect to multiple WiFi networks on my Pi for... reasons.

Other times I like being able to use a better wireless interface than the built-in WiFi module on the Pi 4 or CM4, but don't want to add dtoverlay=disable-wifi in my /boot/config.txt and reboot.

Since Pi OS uses wpa_supplicant, it's actually easy to do this.

First, see what interfaces you have available, e.g. with ip a:

$ ip a
...
3: wlan0: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether e4:5f:01:4e:f0:22 brd ff:ff:ff:ff:ff:ff
4: wlan1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 84:5c:f3:f6:e9:29 brd ff:ff:ff:ff:ff:ff

If you want to specify a network configuration that only applies to wlan1, create a file named /etc/wpa_supplicant/wpa_supplicant-wlan1.conf, and put your network credentials inside:

WiFi 6 gets 1.34 Gbps on the Raspberry Pi CM4

January 1, 2021 Update: My 1.34 Gbps benchmark was flawed. See this GitHub issue and this updated blog post to learn more: WiFi 6 is not faster than Ethernet on the Raspberry Pi.

EDUP Intel AX200 WiFi 6 802.11ax PCIe card in Raspberry Pi Compute Module 4 IO Board

After buying three wireless cards, a new WiFi router, optimizing my process for cross-compiling the Linux kernel for the Raspberry Pi, installing Intel's WiFi firmware, and patching Intel's wireless driver to make it work on the Raspberry Pi, I benchmarked the EDUP Intel AX200 WiFi 6 PCIe card and got 1.34 Gbps of bandwidth between the Raspberry Pi and a new ASUS WiFi 6 router.

This is my story.

AirPort Extreme showing 'Device Not Found'? Here's a fix

If you've had an AirPort Extreme for a while, and recently (within the past year or two) had it go missing from your network (when you open AirPort Utility you get 'Device Not Found'), there's a good chance you ran into the same issue I did. Basically, everything was running great, then one day around August 2016, my Extreme disappeared from the network—even though it was routing Internet traffic for all the devices in my house just as good as ever!

The fix?

  1. Open AirPort utility (it will likely show "Device Not Found").
  2. Unplug your AirPort Extreme, and wait 10 seconds.
  3. Plug it back in, and connect to the WiFi network as soon as possible, then immediately go to the AirPort Utility.
  4. The AirPort should appear and be manageable (by clicking on it) for a brief period—quickly click on it, click Edit, then clear out any Apple IDs in the 'Back to My Mac' section.

AirPort Extreme Back to My Mac Apple ID listing

Setup a FOSCAM WiFi camera directly connected to a Mac via Ethernet

I have two FOSCAM WiFi IP cameras set up in my house (in addition to an outdoor Arlo I use for security purposes), and generally all three of these cameras give a reliable connection and work without much intervention.

Recently, however, one of the FOSCAM cameras decided to stop connecting to the wireless network. I needed to get access to the camera via the wired interface, but I didn't want to have to bring the camera all the way to where my wired networking drops were located, because it's in a bit of an inconvenient area of the basement in the midst of some cleanup we're doing.

So I plugged the FOSCAM directly into my Mac's USB 3.0 ethernet adapter, and got blinky lights... but couldn't connect to the camera because it's wired connection is configured to use DHCP by default, and there's no Bonjour/zeroconf configuration.

To get around this and directly connect to the camera, I did the following:

Getting Gigabit Networking on a Raspberry Pi 2, 3 and B+

tl;dr You can get Gigabit networking working on any current Raspberry Pi (A+, B+, Pi 2 model B, Pi 3 model B), and you can increase the throughput to at least 300+ Mbps (up from the standard 100 Mbps connection via built-in Ethernet).

Note about model 3 B+: The Raspberry Pi 3 model B+ includes a Gigabit wired LAN adapter onboard—though it's still hampered by the USB 2.0 bus speed (so in real world use you get ~224 Mbps instead of ~950 Mbps). So if you have a 3 B+, there's no need to buy an external USB Gigabit adapter if you want to max out the wired networking speed!

Setting up the Edimax EW-7811Un or Tenda W311Mi 802.11b/g/n WiFi Adapter on a Raspberry Pi

Note: On Raspberry Pi models with built-in WiFi (e.g. the Raspberry Pi 3 model B), USB WiFi interfaces will use wlan1 (wlan0 is reserved for the first interface, in this case the internal one).

Since this is maybe the fourth time I've done this process on my Raspberry Pis, I decided to document the process of setting up cheap mini WiFi adapters on a Raspberry Pi A+/B+/2.

This process works great with any USB WiFi adapter that's supported out of the box. My three favorites (due to their inexpensive price and decent connection speed/reliability) are:

2013 MacBook Air WiFi Problems (high latency, dropped connections) [Updated]

Update (3/4/14): Mac OS X 10.9.2 seems to fix at least the latency issue—and possibly dropped connections as well, at least for most users I've spoken with... We'll see!

Update 2 (11/25/14): If you're having trouble with iOS 8 and/or Yosemite, it could be related to AirDrop services over WiFi. Please see WiFried: iOS 8 WiFi Issue

For the past few months, I've been battling my 2013 11" MacBook Air's WiFi problems. I've taken the MacBook to the Genius Bar twice, and have attempted dozens of fixes. Judging by the number of individuals who have posted to this thread on Apple's Support Communities forum, among many other similar threads, I'm not the only MacBook Air owner suffering from WiFi issues like high latency, slow throughput, connection dropouts, and other random problems.

Here are some of the symptoms I and others have encountered:

WiFi for a Small Tech Conference/Meetup

WiFi Routers - AirPort Extreme and AirPort Express

WiFi is awesome for homes and small businesses. Stick a router in a closet somewhere near where you have a cable modem or DSL router, and—boom!—easy Internet and Network access for all 5-10 people/devices within the building.

But, try bringing this setup to a small conference or a meeting of 25+ (or 200+) computer-using people, and you're in for a world of hurt. Some people will get slower-than-dialup access, some people won't be able to connect at all, and others will have strange issues that never happen when you're just using the network by yourself.

The problem(s)

There are many problems that cause WiFi to fail in any setting with more than a few people/devices:

Mac OS X Lion/Mountain Lion - Could not join network/timeout

I was migrating all the data from a friend's old MacBook (which was running Mac OS X Tiger) to her new MacBook Air (running Mac OS X Mountain Lion), and besides a WiFi hiccup, everything went smoothly (I had to clone the old MacBook's drive to a USB disk, then use Setup Assistant to migrate the data from that disk to the new MacBook Air).

During the Setup Assistant, I could easily connect to my WiFi network, but after the migration was complete, I couldn't connect anymore. I kept getting a pesky error: "Could not join [network]. A connection timeout has occurred." (see picture of error dialog here). Looking through Apple's forums and elsewhere was not much help, because this message seems to be a very generic 'something weird happened' error, happening in many different circumstances.

However, knowing that the keychain and old WiFi connection data from the old Mac had transferred over to the new Mac, and knowing that something might've gone screwy with the network information, I decided to do the following:

AirPort Express - Flashing Yellow Light, Not Getting DHCP Address from Cable Modem

I spent the greater part of this afternoon trying to get my AirPort Express to connect to the Internet and share an IP address using a Motorola SB5101 Cable modem (with Charter Internet)... and since the solution was so simple and annoyingly stupid, I thought I'd post it here, for my reference and for anyone else spending an afternoon thinking his AirPort Express is dead.

As it turns out, the cable modem (this one, and likely many others) will only remember the MAC address of the first device it recognized when you last power cycled the modem.

When the Internet went down at my condo yesterday, I turned off my cable modem, plugged my Mac straight into it, turned the modem on, and use the internet via this direct connection for a while. When I plugged the AirPort Express back into the SB5101, I just got a flashing yellow (amber) light, and in the Airport Utility, a notice that the 'Internet Connection wasn't working'.