[iperf3.17] After running UDP at 1000M, the throughput will drop to 0M in 30 mins

I testing the 1G speed. After running UDP at 1000M, the throughput will drop to 0M in 30 mins.
The command is repeted by a script. I tried to change the read/write buffer size to 10K (-l 10K). It still fails.
Could you help provide some suggections?

**Command:**
Server side: `iperf3 -s`
Client side: `iperf3 -u -c 192.168.181.10 --cport 27000 -n 50M -b 1000M -l 5K`

**Client side information:**
```Server listening on 5201 (test #106)
-----------------------------------------------------------
Accepted connection from 192.168.181.11, port 49779
[ 5] local 192.168.181.10 port 5201 connected to 192.168.181.11 port 27000
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-0.48 sec 5.21 MBytes 91.3 Mbits/sec 0.111 ms 105/1173 (9%)
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-0.48 sec 5.21 MBytes 91.3 Mbits/sec 0.111 ms 105/1173 (9%) receiver
-----------------------------------------------------------
Server listening on 5201 (test #107)
-----------------------------------------------------------
Accepted connection from 192.168.181.11, port 49780
[ 5] local 192.168.181.10 port 5201 connected to 192.168.181.11 port 27000
[ ID] Interval Transfer Bitrate Total Datagrams
[ 5] 0.00-1.01 sec 114 MBytes 948 Mbits/sec 23308
[ 5] 1.01-1.01 sec 400 KBytes 988 Mbits/sec 80
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-1.01 sec 114 MBytes 948 Mbits/sec 0.000 ms 0/23387 (0%) sender
-----------------------------------------------------------
Server listening on 5201 (test #108)
-----------------------------------------------------------
Accepted connection from 192.168.181.11, port 49781
[ 5] local 192.168.181.10 port 5201 connected to 192.168.181.11 port 27000
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-0.48 sec 50.7 MBytes 877 Mbits/sec 0.014 ms 67/10442 (0.64%)
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-0.48 sec 50.7 MBytes 877 Mbits/sec 0.014 ms 67/10442 (0.64%) receiver
-----------------------------------------------------------
Server listening on 5201 (test #109)
-----------------------------------------------------------
Accepted connection from 192.168.181.11, port 49782
[ 5] local 192.168.181.10 port 5201 connected to 192.168.181.11 port 27000
[ ID] Interval Transfer Bitrate Total Datagrams
[ 5] 0.00-1.01 sec 114 MBytes 946 Mbits/sec 23303
[ 5] 1.01-2.01 sec 106 MBytes 894 Mbits/sec 21785
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-2.01 sec 220 MBytes 920 Mbits/sec 0.000 ms 0/45087 (0%) sender
-----------------------------------------------------------
Server listening on 5201 (test #110)
-----------------------------------------------------------
Accepted connection from 192.168.181.11, port 49783
[ 5] local 192.168.181.10 port 5201 connected to 192.168.181.11 port 27000
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-1.01 sec 50.1 MBytes 415 Mbits/sec 0.004 ms 199/10462 (1.9%)
[ 5] 1.01-2.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 2.01-3.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 3.01-4.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 4.01-5.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 5.01-6.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 6.01-7.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 7.01-8.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 8.01-9.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 9.01-10.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 10.01-11.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 11.01-12.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 12.01-13.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 13.01-14.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 14.01-15.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 15.01-16.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 16.01-17.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 17.01-18.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 18.01-19.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 19.01-20.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 20.01-21.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 21.01-22.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 22.01-23.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 23.01-24.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 24.01-25.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 25.01-26.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 26.01-27.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 27.01-28.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 28.01-29.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 29.01-30.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 30.01-31.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 31.01-32.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 32.01-33.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 33.01-34.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 34.01-35.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 35.01-36.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 36.01-37.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 37.01-38.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 38.00-39.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 39.00-40.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 40.00-41.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 41.00-42.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 42.00-43.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 43.00-44.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 44.00-45.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 45.00-46.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 46.00-47.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 47.00-48.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 48.00-49.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 49.00-50.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 50.00-51.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 51.00-52.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 52.00-53.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 53.00-54.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 54.00-55.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 55.00-56.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 56.00-57.00 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 57.00-58.02 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 58.02-59.02 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 59.02-60.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 60.01-61.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 61.01-62.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 62.01-63.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 63.01-64.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 64.01-65.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 65.01-66.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 66.01-67.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 67.01-68.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 68.01-69.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 69.01-70.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 70.01-71.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 71.01-72.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 72.01-73.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 73.01-74.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 74.01-75.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 75.01-76.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 76.01-77.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 77.01-78.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 78.01-79.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 79.01-80.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 80.01-81.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 81.01-82.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 82.01-83.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
[ 5] 83.01-84.01 sec 0.00 Bytes 0.00 bits/sec 0.004 ms 0/0 (0%)
```