Lan vs Wifi speed on iperf 3 is 950Mb/s to 250Mb/s

johnw100 · 27 Jun 2022 at 12:38

Hi All

I have an asus router (RT-AX86U wifi 6) and just playing around with setting up a couple of asus mesh pods (RT-AX92U). Not happy with the speeds i`m getting even stood next to the router on wifi.
I`ve tried running iperf3 , with a laptop connected to the asus router. I`m getting around 950Mb/s to another computer on my ethernet. But trying 3 different wifi devices running iperf i`m maxing out at 250Mb/s
Any ideas what could be causing such a difference. Could it be just an overloaded wifi network? There are about 20-30devices running currently, such as a NAS and 3 IP cams.

Thanks

MrRockliffe · 27 Jun 2022 at 12:50

Depends on the laptop and the WiFi card it uses as well - is it WiFi 6?

johnw100 · 27 Jun 2022 at 13:12

I`m using a iphone 13 and a macbook air M1 , those are wifi 6 (AX) , also an samsung android tablet, which isnt but they are all getting the same iperf3 performance on wifi.

johnw100 · 27 Jun 2022 at 14:08

hmm ok so Ive setup openspeedtest on my NAS and its showing around 900Mb/s on wifi. so maybe its my iperf3 settings.

Blackbadger · 27 Jun 2022 at 14:25

If your testing via a computer connected physically to the router, note that only 1 port is 2.5 gigabit and the 4 regualr ones are 1gigabit so you should have the testing computer directly connected to the 2.5 port. Whilst wild claims of 5700mbs wifi are made, they are not physically possible and are aggregate of combined wireless connections in theory. From a cursory glance this router has a max wifi speed of around 900mbps for 1 client to a computer. - this will likely drop when more devices are connected.

Technically with the router in question the best speeds you could achieve are from one wireless device to another wireless device due to the devices weak lan speeds.
30 wifi devices on a consumer lvl router like this is likely to overload it (possibly). It may not have the cpu horsepower to deal with all the traffic on top of the spectrum being congested.

Mesh networks are great for ease of use however do have overheads and often will reduce speed significantly.
Also standing right next to a router isn't often ideal - approx 3m is often the sweet spot.

sandys · 27 Jun 2022 at 15:23

run with more parallel connections wifi breaks up the traffic.

johnw100 · 27 Jun 2022 at 15:48

Thanks. This was my openspeedtest from my NAS wired on my NAS from my PC on a 2.5g connection.

And this from my iphone 13 wifi

So not sure why using iperf3 my iphone,etc seemed much slower speeds to a local PC which was down to around 300mb/sec
Have just tried on my 2.5gb PC in my office and i`m getting around 700Mb/sec on wifi via iperf.

WJA96 · 28 Jun 2022 at 05:37

johnw100 said:
Thanks. This was my openspeedtest from my NAS wired on my NAS from my PC on a 2.5g connection.

And this from my iphone 13 wifi

So not sure why using iperf3 my iphone,etc seemed much slower speeds to a local PC which was down to around 300mb/sec
Have just tried on my 2.5gb PC in my office and i`m getting around 700Mb/sec on wifi via iperf.

@sandys explained why - iPerf needs multiple connections enabled.

Anyway - it seems your issue isn’t an issue/is resolved. Yay!