Double Nat Issue (LTE modem + OpenWrt router)

[Lynx]

OK thanks. Also, isn't this a bit low for 1 Gbit/s connection?

root@OpenWrt:~# iperf3 -c 192.168.0.1
Connecting to host 192.168.0.1, port 5201
[  5] local 192.168.0.2 port 50296 connected to 192.168.0.1 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  59.1 MBytes   496 Mbits/sec    0    585 KBytes
[  5]   1.00-2.00   sec  58.9 MBytes   494 Mbits/sec    0    619 KBytes
[  5]   2.00-3.00   sec  58.5 MBytes   491 Mbits/sec    0    619 KBytes
[  5]   3.00-4.00   sec  58.9 MBytes   494 Mbits/sec    0    619 KBytes
[  5]   4.00-5.00   sec  57.8 MBytes   484 Mbits/sec    0    656 KBytes
[  5]   5.00-6.00   sec  58.5 MBytes   492 Mbits/sec    0    656 KBytes
[  5]   6.00-7.00   sec  57.2 MBytes   480 Mbits/sec    0    973 KBytes
[  5]   7.00-8.00   sec  59.8 MBytes   501 Mbits/sec    0    973 KBytes
[  5]   8.00-9.00   sec  59.4 MBytes   497 Mbits/sec    0    973 KBytes
[  5]   9.00-10.00  sec  55.9 MBytes   469 Mbits/sec    0    973 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   584 MBytes   490 Mbits/sec    0             sender
[  5]   0.00-10.00  sec   580 MBytes   487 Mbits/sec                  receiver

iperf Done.
root@OpenWrt:~# iperf3 -c 192.168.0.1 -R
Connecting to host 192.168.0.1, port 5201
Reverse mode, remote host 192.168.0.1 is sending
[  5] local 192.168.0.2 port 50398 connected to 192.168.0.1 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  93.7 MBytes   786 Mbits/sec
[  5]   1.00-2.00   sec  93.3 MBytes   782 Mbits/sec
[  5]   2.00-3.00   sec  85.9 MBytes   720 Mbits/sec
[  5]   3.00-4.00   sec  86.6 MBytes   727 Mbits/sec
[  5]   4.00-5.00   sec  92.3 MBytes   774 Mbits/sec
[  5]   5.00-6.00   sec  88.2 MBytes   740 Mbits/sec
[  5]   6.00-7.00   sec  90.1 MBytes   756 Mbits/sec
[  5]   7.00-8.00   sec  89.9 MBytes   755 Mbits/sec
[  5]   8.00-9.00   sec  90.0 MBytes   755 Mbits/sec
[  5]   9.00-10.00  sec  95.0 MBytes   797 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   905 MBytes   759 Mbits/sec    0             sender
[  5]   0.00-10.00  sec   905 MBytes   759 Mbits/sec                  receiver

iperf Done.
root@OpenWrt:~#

[psherman]

Most embedded devices cannot source/sink packets nearly as fast as they can route/switch them. That is because the former is CPU intensive, while the latter is reliant on specialized routing and switching hardware that can move data at high speeds.

So when testing from (or to) a non-general-purpose router ("general purpose" being one that has a full featured CPU like x86 or a more powerful ARM chip), it is common to get lower iPerf scores than if you route through the device.