urtwn instable on Beaglebone Black

[Otacílio]

Dears

I'm using a beaglebone black to stream video over UDP. I wrote a 
software and have tested it using a urtwn device + webcam Logitech C920. 
All is connected using a USB hub with external power source. So urtwn 
and webcam, both are plugged in the same USB hub. When I plug the hub 
and run my software on a old notebook intel centrino with FreeBSD 
11.0-RC2 AMD64 all works fine. Last night the system stream video all 
night. But, when I replace the notebook by beaglebone black running 
FreeBSD 11.0-RC1 with the same USB HUB, the same wrtwn device and same 
camera, randomly after some time the beaglebone black network shutdown 
and terminal shows this messages :


Network is down
% urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.
urtwn0: ieee80211_crypto_encap returns NULL.

Then, I need to run

/etc/rc.d/netif stop

/etc/rc.d/netif start

To enable network again. So, someone can give me a hit about what can be 
this and how to fix?

Thanks a lot

[]'s

-Otacilio