Recently I try latest stable version openwrt, looks like the open source MT76 driver is much stable and fast now.

iperf3 -c 192.168.1.1
Connecting to host 192.168.1.1, port 5201
[  5] local 192.168.1.231 port 60121 connected to 192.168.1.1 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  5.33 MBytes  44.7 Mbits/sec                  
[  5]   1.00-2.00   sec  5.50 MBytes  46.1 Mbits/sec                  
[  5]   2.00-3.00   sec  5.34 MBytes  44.7 Mbits/sec                  
[  5]   3.00-4.00   sec  4.67 MBytes  39.3 Mbits/sec                  
[  5]   4.00-5.00   sec  5.47 MBytes  45.8 Mbits/sec                  
[  5]   5.00-6.00   sec  5.03 MBytes  42.3 Mbits/sec                  
[  5]   6.00-7.00   sec  4.93 MBytes  41.3 Mbits/sec                  
[  5]   7.00-8.00   sec  5.07 MBytes  42.6 Mbits/sec                  
[  5]   8.00-9.00   sec  4.95 MBytes  41.5 Mbits/sec                  
[  5]   9.00-10.00  sec  5.13 MBytes  43.0 Mbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-10.00  sec  51.4 MBytes  43.1 Mbits/sec                  sender
[  5]   0.00-10.09  sec  51.3 MBytes  42.7 Mbits/sec                  receiver

iperf Done.

This is good 🙂 Next firmware will base on this driver and I do not have to patch it anymore.