IPERF3 slow between two devices


Device 1 > Router = 200Mbits
Device 2 > Router = 200Mbits

The issue when testing between devices

Device 1 > Device 2 = 100Mbits and less

The WiFi link speed above 400Mbits in all devices

Any insights?

If both devices connect to the same Wifi (Router), then it is expected to see half speed or so. Packets need to go from device 1 to device 2 over the same shared medium.

What mode and what band width on both?

for a long time the blame was on the WiFi's nature and it's theoretical performance and this changed completely since WiFi 6 announcement, the blame will shift now to the WiFi card or the software and protocols used in the transfer process.

the experiment in the first post was on TPlink AX20 router which released in DEC 2019, the theoretical wifi speed with 5Ghz AX band is 1.2Gbps, both of the devices are capable of AC 80hz width which achieved with 433Mbps link however the actual speed is far less as stated before, the first device is android phone with WiFi 6 connectivity, the second is a PC with Windows OS (tried with Linux and endup with same result) and WiFi 5 connectivity.

When I tried the test between the phone and android tablet both capable of WiFi 6 I achieved almost 1Gbps, an 80% of the announced speed rates.