TX2 WIFI Performance too low

We’re test TX2 built-in WIFI transfer speed with iperf tool,
unfortunately,My test result is ~55.1 Mbits/sec.
192.168.3.100 is the win10 host address.
The hardware connection information:

TX2 connect to TP-LINK(TL-WDR7300 Gbit) router by wifi
Win10 host connect to TP-LINK(TL-WDR7300 Gbit) router by wifi.

Perform the following test command on TX2:
iperf -u -c 192.168.3.100 -f m -i 3 -b 1000MB -t 300

Client connecting to 192.168.3.100, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size: 0.22 MByte (default)

[ 3] local 192.168.3.102 port 55565 connected with 192.168.3.100 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 3.0 sec 15.7 MBytes 44.0 Mbits/sec
[ 3] 3.0- 6.0 sec 18.9 MBytes 52.8 Mbits/sec
[ 3] 6.0- 9.0 sec 19.9 MBytes 55.7 Mbits/sec
[ 3] 9.0-12.0 sec 19.7 MBytes 55.1 Mbits/sec
[ 3] 12.0-15.0 sec 19.8 MBytes 55.4 Mbits/sec
[ 3] 15.0-18.0 sec 19.7 MBytes 55.1 Mbits/sec
[ 3] 18.0-21.0 sec 19.4 MBytes 54.3 Mbits/sec
[ 3] 21.0-24.0 sec 20.0 MBytes 56.0 Mbits/sec
[ 3] 24.0-27.0 sec 19.2 MBytes 53.7 Mbits/sec
[ 3] 27.0-30.0 sec 19.7 MBytes 55.1 Mbits/sec
[ 3] 30.0-33.0 sec 18.5 MBytes 51.8 Mbits/sec
[ 3] 33.0-36.0 sec 19.3 MBytes 53.8 Mbits/sec
[ 3] 36.0-39.0 sec 16.2 MBytes 45.4 Mbits/sec
[ 3] 39.0-42.0 sec 14.3 MBytes 40.1 Mbits/sec
^C[ 3] 0.0-43.8 sec 272 MBytes 52.0 Mbits/sec
[ 3] Sent 200627 datagrams
read failed: Connection refused
[ 3] WARNING: did not receive ack of last datagram after 2 tries.

if just have the win10 host connect to Router by Wired cable, the speed will been about 400 Mbit/Sec.

I’m using JetPack3.3 R28.2.1.
Are there any things missing with driver or config?

Anyone have run into this issues?