[SOLVED] Wi-Fi 6 internet blazing fast but file transfer very slow ?

Mar 10, 2022
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I have 2 Win10 PCs, both with Wi-Fi 6 AX201 cards installed. Both connected to an AT&T BGW320-500 modem with 1Gbps fiber connection. When I do a speed test on either PC, it returns 970 Mbps or so up and down, but when I transfer a 1Gig file from one PC to the other over the network, 90% of the time it copies at less than 20MBps. The other 10% of the time it'll transfer at between 80-95MBps. I've tried switching channels, updating firmware, switching from 5GHz to 2.4GHz but that just makes it go even slower. I don't get why sometimes it's really fast, but most of the time it's considerably slower. Thanks for any help or suggestions!
 
Solution
I am extremely surprised you get over 900mbps on wifi. You are one of the very lucky people that can actually get 160mhz radio channels and have very little interference. I suspect you are fairly close to the router also.

Your main problem is wifi is half duplex only 1 device can transmit at the same time. You now have 3 devices and your data is actually being sent 2 times. It goes from each pc to the router and then to the other pc. All this traffic is sharing the same radio bandwidth.

So even at best you would expect 1/2 since you are actually sending the data twice over the wifi. Also the more traffic you send the more chance there is for data to interfere with each other require retransmission slowing things down even...
I am extremely surprised you get over 900mbps on wifi. You are one of the very lucky people that can actually get 160mhz radio channels and have very little interference. I suspect you are fairly close to the router also.

Your main problem is wifi is half duplex only 1 device can transmit at the same time. You now have 3 devices and your data is actually being sent 2 times. It goes from each pc to the router and then to the other pc. All this traffic is sharing the same radio bandwidth.

So even at best you would expect 1/2 since you are actually sending the data twice over the wifi. Also the more traffic you send the more chance there is for data to interfere with each other require retransmission slowing things down even more.

There is a different method you can set wifi 6 up so it shares the radio bandwidth differently, in effect making mulitple smaller radio band for different device. This reduces the collisions but it also cuts the speed substantially.

For you average person they would be very happy if they got 20MByte rates between 2 machines using wifi. Most people are lucky to get 300mbps on speed test with a single machine because of all the interference from the neighbors wifi and the inability to get 160mhz radio bands because of say weather radar.

Not sure what to recommend other than to try to not use wifi for this application. Ethernet cables would be optimum but if you have coax cable near the pc and router you could conisder MoCA adapters which can get full gigabit speeds.
 
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