I received a Raspberry Pi 3 lately and gave it a spin right away. I immediately ran into an issue with the integrated WIFI adapter. I had downloaded the latest Raspbian Jessie Lite, expecting it to run smoothly. This was the case except for this one issue. The point is: choose the right channel, see below.
Now, I am really thrilled to make some use of the Pi. For some of the projects, I'll need some external equipment. Whenever I have something to present, I'll probably write another entry here. The areas I'm having in mind currently are home automation, photography, and possibly music.
Choose the right channel
When setting up WIFI for the first time, I got to see a Kernel Oops pretty much right after enabling it. What had happened? Apparently, the settings I chose were not quite compatible with the embedded WIFI adapter's capabilities. It only supports channels 1-11 in the 2GHz range, and my home network was setup for automatic channel selection. The last selected channel I saw before I discovered what was going wrong was channel 13, which is outside of this range. Explicitly setting the channel to sth. below 12 made the Pi use the WIFI network. So, when you run into such issues, please check the channel to which your network is set and change it accordingly.
You can check the channels that your Pi supports by:
pi@raspberrypi:~ $ sudo iwlist wlan0 channel
wlan0 11 channels in total; available frequencies :
Channel 01 : 2.412 GHz
Channel 02 : 2.417 GHz
Channel 03 : 2.422 GHz
Channel 04 : 2.427 GHz
Channel 05 : 2.432 GHz
Channel 06 : 2.437 GHz
Channel 07 : 2.442 GHz
Channel 08 : 2.447 GHz
Channel 09 : 2.452 GHz
Channel 10 : 2.457 GHz
Channel 11 : 2.462 GHz
Current Frequency:2.412 GHz (Channel 1)
pi@raspberrypi:~ $As you can see, mine supports channels 1-11 in the current configuration. There are reports of people having updated the firmware to support channel 13 as well1. However, there are other voices suggesting to wait with the update2.
Additional Symptoms
When trying to find out what was going wrong, I tried scanning for networks within reach from my Pi and cross-checked it with the results from my laptop. Oddly enough, I found an almost mutually exclusive set of networks. "Almost", because after scanning for a while I found some overlap, i.e. networks that were picked up by both devices. Now, the PI only found networks with very low signal strength, whereas I could certainly see networks with much stronger signal from my laptop. I'm sitting in a different location now, but I seem to remember that most of the other networks were on the higher channels.
I guess the signal level of the networks the Pi picked up were so low that my laptop had a hard time receiving them. And the good networks, i.e. my own network and some of the neighbors' networks, were all on channels 12/13 and others.
LinSSID3 was the tool I used for debugging this problem, and it quite well displays the signal strengths of available networks, among other information.