LAN speed is slower than internet speed (iperf test)

[JulienG]

I have a RT-AC88U connected to internet.

I have been performing the 2 following tests

Both are performed which connected in 5 GHz wifi closed to the RT-AC88U router (Wifi TX Rate >600 Mbps)

Test 1 (between the 2 laptops)
Laptop A (Mac no firewall) 1 is running iperf3 in client mode
Laptop B (Mac no firewall - IP: 192.168.1.135) is running iperf3 in server mode
iperf3 -c 192.168.1.135 -t 20 -R —> 120 Mbits/sec
iperf3 -c 192.168.1.135 -t 20 —> 147 Mbits/sec

Test 2 (from Laptop A to internet):
iperf3 -c ping.online.net -p 5206 -R —> 390 Mbits/sec (consistent with Speedtest)
iperf3 -c ping.online.net -p 5206 —> 380 Mbits/sec (consistent with Speedtest)

Then I ran 2 others similar tests from an Access Point wired to the RT-AC88U and I have same results

Why do I have such low speed between my 2 laptops ? why is one third of the internet speed?
Where do yo think the issue could be located in the router set up ?

Thanks
Julien

 

[K-2SO]

Both are performed which connected in 5 GHz wifi

Your total WiFi bandwidth is shared between WiFi clients. Both your Mac's are using the same radio at the same time. When you test one Mac to wired connection, your ISP modem or NAS, it can use the full bandwidth. Hit the speedtest on both Mac's at the same time and you'll understand better what is happening.

PS. It's your WLAN speed. Not LAN speed.

 

[JulienG]

Your total WiFi bandwidth is shared between WiFi clients. Both your Mac's are using the same radio at the same time. When you test one Mac to wired connection, your ISP modem or NAS, it can use the full bandwidth. Hit the speedtest on both Mac's at the same time and you'll understand better what is happening.

PS. It's your WLAN speed. Not LAN speed.

I have put laptop on an Access Point which is connected through a 1 GB ethernet link and same issue.

120 Mbits/sec looks very low for me.

 

[K-2SO]

I have put laptop on an Access Point

Test your LAN speeds. If close to ISP speeds, look for WiFi issues.
Your WiFi speeds should be about half of Tx/Rx rates you see in Wireless Log.

 

[JulienG]

I will check the LAN first. I suspect Laptop B has a bad performance wifi card.