In the /var/log/messages file of my Raspberry Pi, which is connected through WiFi to my home WLAN, I repeatedly noticed this error message:
smsc95xx 1-1.1:1.0 eth0: unexpected urb length 0
Furthermore, I got “no route to host” messages when attempting to ssh to my RasPi. At the same time I couldn’t connect to lighttpd. Some research with Google suggested, that there might be a problem with the USB driver. Symptoms are characterized by fluctuating transfer rates and response times as well as bad WiFi connection quality leading to delayed keyboard response or garbled input when using ssh. Fortunately, there is a workaround: