I know that there are similiar questions out there but not worked for me. I've set up a static ip for my wlan0 interface. that works well when I'm also connected via ethernet. but as soon as I disconnect the cable I can't ping to the defined wlan0 ip or ssh. the strange thing is that my router knows that my pi is connected via wifi.
If I boot with only the wifi dongle...it still does not work.
here is my interfaces file:
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet manual
allow-hotplug wlan0
iface wlan0 inet manual
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface sky inet static
address 192.168.1.41
netmask 255.255.255.0
gateway 192.168.1.1
iface default inet dhcp