Arch Linux

masm

Member

Registered: 2011-10-21

Posts: 8

rtl8192cu based wireless USB adapter not working

I have a tp-link wn821n v4 USB adapter that uses a rtl8192cu chip. I cannot get it to connect to my network.
It works on a Windows machine.

I try to follow the steps for manual setup in the wireless wiki page, and when I get to the step to scan the network,
it sometimes works, other times it does not work (no networks found).  When it does work (it finds my network), it
stops working less than a minute later and does not work again until I reconnect it.

When I connect the adapter I get this from dmesg:

[    1.754882] r8169 0000:02:00.0: eth0: RTL8168evl/8111evl at 0xffffc90006336000, bc:5f:f4:5e:f5:d8, XID 0c900800 IRQ 49
[    1.781502] rtl8192cu: Chip version 0x11
[    1.866338] rtl8192cu: MAC address: 64:70:02:15:ec:35
[    1.866340] rtl8192cu: Board Type 0
[    1.866573] rtlwifi: rx_max_size 15360, rx_urb_num 8, in_ep 1
[    1.866588] rtl8192cu: Loading firmware rtlwifi/rtl8192cufw.bin
[    1.866643] usbcore: registered new interface driver rtl8192cu
[    1.870317] ieee80211 phy0: Selected rate control algorithm 'rtl_rc'
[    1.870825] rtlwifi: wireless switch is on

After this:

$ sudo iw dev wlan0 info
Interface wlan0
        ifindex 3
        wdev 0x1
        addr 64:70:02:15:ec:35
        type managed
        wiphy 0
        channel 1 (2412 MHz) NO HT

$ sudo ip link set wlan0 up

$ dmesg | tail -3
[ 3819.359596] rtl8192cu: MAC auto ON okay!
[ 3819.392312] rtl8192cu: Tx queue select: 0x05
[ 3819.761149] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready

$ sudo iw dev wlan0 scan
$

the scanning does not return anything. As I said, it sometimes return my network for the first about 5 tries,
and then it stops working and does not work again until I disconnect it and connect again.

Is the "wlan0: link is not ready" message the problem?

This might be a driver bug, but I searched around I don't see anyone complaining about this problem. Has anyone
seen something like this?

masm

Member

Registered: 2011-10-21

Posts: 8

Re: rtl8192cu based wireless USB adapter not working

I have disabled wpa security, and now I can connect  to the AP

$ sudo iw dev wlan0 connect TP-LINK_FB739C
$ sudo iw dev wlan0 link
Connected to 90:f6:52:fb:73:9c (on wlan0)
        SSID: TP-LINK_FB739C
        freq: 2412
        RX: 2550 bytes (22 packets)
        TX: 715 bytes (8 packets)
        signal: -35 dBm
        tx bitrate: 150.0 MBit/s MCS 7 40Mhz short GI

        bss flags:      short-preamble short-slot-time
        dtim period:    0
        beacon int:     100

But it still fails to get a dynamic IP:

$ sudo dhcpcd wlan0
dhcpcd[2319]: version 5.6.3 starting
dhcpcd[2319]: wlan0: sending IPv6 Router Solicitation
dhcpcd[2319]: wlan0: broadcasting for a lease
dhcpcd[2319]: wlan0: sending IPv6 Router Solicitation
dhcpcd[2319]: wlan0: sending IPv6 Router Solicitation
dhcpcd[2319]: wlan0: sending IPv6 Router Solicitation
dhcpcd[2319]: wlan0: no IPv6 Routers available
dhcpcd[2319]: timed out

I tried to set a static IP and then ping another computer in the network
but it didn't work either.

While connected to AP, scan works every time (it does not stop working as it used to
when using WPA).

Anyone has any idea?
Any ideas?