Asus RT-N66U problem with Wifi

Not working wifi, very weak signal. Build firmware using the b43 driver.

Not working or very weak signal ?

Recheck your question

–°an say that wifi is not working. Connects 1 time after reboot, works 10 minutes while the signal is weak, then the connection is lost.
Can try to build the firmware with a different wifi driver? Maybe someone knows a working driver?

b43 has only very basic support for BCM4331, I don't really expect that to change significantly either (so don't expect 802.11n performance).

can't understand why in dd-wrt it works in 802.11n mode and LEDE can't work in it. may be someone explains?

Because DD-WRT uses Broadcom proprietary driver while LEDE uses b43 driver

so how to use proprietary driver in LEDE?

You really cant