Does your Internet connection work for the gateway (can you ping 184.108.40.206 from OpenWRT)? Did you get a success message when uploading the Arduino sketch? Did you set the correct EUI at the TTN Console Gateway section?
My LG01 runs very stable, I use it for testing at home. The only bad thing is that it is superslow (takes a min. of 10 seconds to receive/forward a packet).