I'm using a beaglebone to stream videos over wifi. For this, I'm testing two
wifi adapters:

rtwn0: MAC/BB RTL8188CUS, RF 6052 1T1R

run0: MAC/BBP RT5390 (rev 0x0502), RF RT5370 (MIMO 1T1R), address
e8:4e:06:3c:fd:5d

Both adapters works fine at low bit rate (300 Kbps), but when I use a high
bi rate, for example 3 Mbps the  adapter RTL8188CUS hangs up with the
message below:

===============================================================================

rtwn0: at uhub2, port 3, addr 4 (disconnected)
rtwn0: device timeout
Network is down
[ota@beaglebone ~/workspace/SOFTWARE_Espelho/Capture]$ rtwn0:
r92c_handle_c2h_task: C2H report 15 (len 15) was not handled
Apr 12 10:58:06 beaglebone openvpn[759]: write UDP: Network is down
(code=50)
Apr 12 10:58:10 beaglebone wpa_supplicant[1436]: ioctl[SIOCS80211, op=20,
val=0, arg_len=7]: Can't assign requested address
rtwn0: ieee80211_crypto_encap returns NULL.
rtwn0: ieee80211_crypto_encap returns NULL.
Apr 12 10:58:10 beaglebone wpa_supplicant[1436]: ioctl[SIOCS80211, op=103,
val=0, arg_len=128]: Device not configured
Apr 12 10:58:16 beaglebone last message repeated 6 times
Apr 12 10:58:16 beaglebone openvpn[759]: write UDP: Network is down
(code=50)
Apr 12 10:58:17 beaglebone wpa_supplicant[1436]: ioctl[SIOCS80211, op=103,
val=0, arg_len=128]: Device not configured

===============================================================================
This occurs only with the RTL8188CUS (rtwn). The adapter RT5390 (run) works
fine on both situation and never hangs up. So, the FreeBSD version is:

FreeBSD beaglebone 12.0-CURRENT FreeBSD 12.0-CURRENT #1 r316378M: Thu Apr  6
01:08:51 -03 2017 ota@beaglebone:/mnt/obj/mnt/src/sys/BEAGLEBONE  arm