"no buffer space available" EDIMAX EW-7811UN Wireless USB Adapter

[Andriy Voskoboinyk]

Sun, 10 Apr 2016 14:02:02 +0300 було написано Dave Cottlehuber  
<dch at skunkwerks.at>:

> Hi,
>
> I got an EDIMAX EW-7811UN Wireless USB Adapter [1]
> (150 Mbit/s, IEEE802.11b/g/n) to use on a few systems that
> don't yet have supported onboard adapters.
>
> While using this I get `no buffer space available` regularly,
> including from dhclient.

It an old bug - dhclient listens to the RTM_IEEE80211_ASSOC event, and,
when it arrives, tries to send a request. However, in an encrypted network,
this event goes before 4-way handshake occurs - so, there is a chance,
that packet will be discarded because there is no key available yet.
(also, this event is used by wpa_supplicant, so we cannot just send it
later)

> This sometimes requires me to
> hard reboot to regain network connectivity. Is there anything
> I can do about this?
>

There is some instability with RTL8188CUS chipset (sometimes its just
stops working); you can restart it with
1) ifconfig wlan0 down
2) ifconfig wlan0 destroy
3) usbconfig -d <device> power_off
4) usbconfig -d <device> power_on

> BTW specific recommendations on better-supported USB widgets
> are welcome.

For me, TP-Link TL-WN725N works a bit better (but there may be some
better supported chipsets).