I've been using 802.11 on Linux now for over a decade, and to be honest, it's still a pretty sad experience. It works well enough that I mostly don't care... but when I care, and try to dig deeper, it always ends up in the answer “this is just crap”.

I can't say exactly why this is; between the Intel cards I've always been using, the Linux drivers, the firmware, the mac80211 layer, wpa_supplicant and NetworkManager, I have no idea who are supposed to get all these things right, and I have no idea how hard or easy they actually are to pull off. But there are still things annoying me frequently that we should really have gotten right after ten years or more:

Why does my Intel card consistently pick 2.4 GHz over 5 GHz? The 5 GHz signal is just as strong, and it gives a less crowded 40 MHz channel (twice the bandwidth, yay!) instead of the busy 20 MHz channel the 2.4 GHz one has to share. The worst part is, if I use an access point with band-select (essentially forcing the initial connection to be to 5 GHz—this is of course extra fun when the driver sees ten APs and tries to connect to all of them over 2.4 in turn before trying 5 GHz), the driver still swaps onto 2.4 GHz a few minutes later!

Rate selection. I can sit literally right next to an AP and get a connection on the lowest basic rate (which I've set to 11 Mbit/sec for the occasion). OK, maybe I shouldn't trust the output of iwconfig too much, since rate is selected per-packet, but then again, when Linux supposedly has a really good rate selection algorithm (minstrel), why are so many drivers using their own instead? (Yes, hello “iwl-agn-rs”, I'm looking at you.)

Connection time. I dislike OS X pretty deeply and think that many of its technical merits are way overblown, but it's got one thing going for it; it connects to an AP fast. RFC4436 describes some of the tricks they're using, but Linux uses none of them. In any case, even the WPA2 setup is slow for some reason, it's not just DHCP.

Scanning/roaming seems to be pretty random; I have no idea how much thought really went into this, and I know it is a hard problem, but it's not unusual at all to be stuck at some low-speed AP when a higher-speed one is available. (See also 2.4 vs. 5 above.) I'd love to get proper support for CCX (Cisco Client Extensions) here, which makes this tons better in a larger Wi-Fi setting (since the access point can give the client a lot of information that's useful for roaming, e.g. “there's an access point on thannel 52 that sends its beacons every 100 ms with offset 54 from mine”, which means you only need to swap channel for a few milliseconds to listen instead of a full beacon period), but I suppose that's covered by licensing or patents or something. Who knows.

With now a billion mobile devices running Linux and using Wi-Fi all the time, maybe we should have solved this a while ago. But alas. Instead we get access points trying to layer hacks upon hacks to try to force clients into making the right decisions. And separate ESSIDs for 2.4 GHz and 5 GHz.

Augh.