I installed OpenWRT a few days ago on my Asus RTN12E_B1.
So far it worked pretty fine except the WiFi. It is extremly slow and always crash. I connected my Smartphone with the WiFi. The Network speed is between 2 and 42 Mbps and varies very much.
My Router should support up to 300 Mbps WiFi speed. With the original Firmware and also the Padavan Firmware I get a constant connection with 144 Mbps.
Then there are the crashes. My Smartphone randomly disconnect from the Wifi and can't establish a connection after it. I need to restart the WiFi on the Router manually, to get a connection again..
I tested it with my Laptop and other Smartphones as well. But the LAN-connection is pretty fast and there are no differences compared to original firmware or padavan.
I tried so many different Wifi-Settings but nothing helped. I tried OpenWRT 18.06.1 and 18.06.2
Both Wifi-Devices are literally next to my Router.
Edit: I personally think it is an error with the WiFi-Driver. Are there updates for my mt76 drivers and how can I install them?