14.04 Server can't connect to Wifi with ifup; wap_supplicant throws "ioctl[SIOCSIWENCODEEXT]: Invalid argument"

Question

I moved my 14.04 home server to a new apartment that can only access the internet via Wifi. This machine used to have a desktop version of 12.04 that connected to wifi fine via network-manager (so I think the hardware and drivers are ok), but I don't want a GUI or network-manager on this install; I want it to run as a headless server for ssh, nfs, and as a webhost, among other things. After I installed 14.04 Server, but before I moved, it connected just fine to the LAN in my old apt. But I can't get it connected over Wifi.

I tried configuring /etc/network/interfaces as done here, but to no avail. Here is my configuration:

auto lo
iface lo inet loopback

auto wlan0
iface wlan0 inet static
    address 192.168.1.151
    netmask 255.255.255.0
    gateway 192.168.1.1
    wpa-ssid "my ssid"
    wpa-psk <passphrase>
    dns-nameservers 8.8.8.8 8.8.4.4

When I run ifdown wlan0 && ifup -v wlan0, I get:

Configuring interface wlan0=wlan0 (inet)
run-parts --verbose /etc/network/if-pre-up.d
run-parts: executing /etc/network/if-pre-up.d/ethtool
run-parts: executing /etc/network/if-pre-up.d/wireless-tools
run-parts: executing /etc/network/if-pre-up.d/wpasupplicant
wpa_supplicant: wpa-driver nl80211,wext (default)
wpa_supplicant: /sbin/wpa_supplicant -s -B -P /var/run/wpa_supplicant.wlan0.pid -i wlan0 -D nl80211,wext -C /var/run/wpa_supplicant
Starting /sbin/wpa_supplicant...
wpa_supplicant: waiting for "var/run/wpa_supplicant.wlan0.pid": 0 (max. 5)
wpa_supplicant: creating sendsigs omission pidfile: /run/sendsigs.omit.d/wpasupplicant.wpa_supplicant.wlan0.pid
wpa_supplicant: ctrl_interface socket located at /var/run/wpa_supplicant/wlan0
wpa_supplicant: configuring network block -- 0
wpa_supplicant: wpa-ssid "my ssid" -- OK
wpa_supplicant: wpa-psk ***** -- OK
wpa_supplicant: enabling network block 0 -- OK
ip addr add 192.168.1.1/255.255.255.0 broadcast 192.168.1.255        dev wlan0 label wlan0
ip link set dev wlan0   up
  ip route add default via 192.168.1.1   dev wlan0
run-parts --verbose /etc/network/if-up.d
run-parts: excuting /etc/network/if-up.d/000resolvconf
run-parts: excuting /etc/network/if-up.d/bind9
run-parts: excuting /etc/network/if-up.d/ethtool
run-parts: excuting /etc/network/if-up.d/ntpdate
run-parts: excuting /etc/network/if-up.d/openssh-server
run-parts: excuting /etc/network/if-up.d/upstart
run-parts: excuting /etc/network/if-up.d/wpa-supplicant

Looks good, but if I try to ping 192.168.1.1, I get

PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
From 192.168.1.151 icmp_seq=1 Destination Host Unreachable

--- 192.168.1.1 ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms 

If I ping google.com, all I get is unknown host.

I've tried configuring with wpa_supplicant similar to this post, and got the same ioctl[SIOCSIWENCODEEXT]: Invalid argument error. My /etc/wpa_supplicant.conf reads in it's entirety:

network={
    ssid="my ssid"
    #psk="<passphrase>"
    psk=<hexdump>
}

Halfway through writing this question I realized if I flagged the nl80211 driver instead of wext, I no longer get the error, but I'm still unable to ping my router or Google. When I run iwconfig, I get:

wlan0    IEEE 802.11bgn  ESSID:off/any
         Mode:Managed  Frequency:2.417 GHz Access Point: Not-Associated
         Tx-Power=20 dBm
         Retry short limit:7   RTS thr=2347 B   Fragment thr:off
         Encryption key:off
         Power Management:on

My network card is a RTL8191SEvB PCI card by Realtek, driver=rtl8192se

The problem becomes more opaque the more I troubleshoot. I just don't know where the issue lies.

Any suggestions?