Question Why is my 2.4G so much slower than 5G

hw_user

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Mar 11, 2010
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I am using the ISP provided CGN3 modem/router. I used my phone (Speedtest by Ookla App) to perform speed test. I sat 5 feet away from the modem with nothing in between. Wifi Analyzers App shows 2.4G SSID -33dbm and 5G SSID -34dbm. My ISP package is 75/10. The test results shows 73.4 Mb down and 10 Mb up when my phone is connected to 5G SSID. But the speed is only 33.4 Mb down and 10 Mb up when my phone is connected to the 2.4G SSID. It seems that 2.4G is only half of the speed of 5G. Is this normal ?
 
Did you never notice that when they state numbers like 1200 they say 300 on 2.4 and 900 on 5g.

They key thing that makes 5g faster is that the radio bands can be 80mhz wide. On 2.4g they can at maximum be 40mhz and many times are only 20mhz. So this alone makes 5g at least 2 times as fast. They also use a more dense data encoding on the 5g than 2.4g.

This is even more of a difference if you happen to have very high end wiifi6 (802.11ax) devices. These devices can use 160mhz of radio bandwidth on the 5g band so they are in theory 2 times faster than 802.11ac using 5g and 4 times as fast as 2.4g. Now in real life it does not work all that well yet. Most devices are only 80mhz like 802.11ac. Coming "soon" we are going to have a new radio band in the 6g range. This has massive amounts of bandwidth so it is easy to get 160mhz chunks of bandwidth. So when wifi6E gets common you likely will see it be more than 4 times as fast as running on the 2.4g band.

Now the thing that makes this messy is 2.4g passes through walls easier. So if you have a lot of walls eating the signal 2.4g can be faster then running on 5g.
 

hw_user

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Thanks for the quick response. I understand that 5HG is faster and travel shorter distance while 2.4 G is slower but travels longer. What I am trying to find out id if what I observed is normal (i.e. is there any problem with my equipment or set up). I believe , my ISP is providing what they promise because I am getting 73.4/10 with my 5G connection. I am getting exactly 75/10 using ethernet connection. I believe an average 802.11n 2.4G adapter should get at least 100 mbs. Why I am only getting 33.4 Mb when my phone is connected to my 2.4G SSID ? To further isolate the issue, I used my laptop in place of my phone, the result is similar 34 Mb down with 2.4G and 74 Mb down with 5G. So this means it is not my phone's 2.4G adapter. This may mean that the problem is the 2.4G of the CGN3 modem/router. I set up an wired access point using an old linksys E3200 by connecting the E3200 to CGN3 using ethernet LAN and set up wireless SSIDs (E3200_2.4 and E3200_5). All these set ups are within 5 or 6 feet distance (i.e. no signals travelling through any walls). The result is similar. 70 Mb down when connect to E3200_5 and 30 Mb down when connect to E3200_2.4. With the AP set up, I am using the 2.4G radio of the E3200 instead of the CNG3. This seems to says that both the 2.4G radio of the E3200 2.4G radio are similar (could be both bad or both OK).
In summary, I need to understand why I am only getting about half of what my ISP provide on 2.4G ?
 
This is very hard to say wifi pretty much does what it thinks is best and you can do little to change it.

You need to look at the number you see on the status of the nic on your pc. This represents the encoding and indirectly the speed. It could be that the router is being "smart" and detecting neighbors using the 2.4g band and dropping to 20mhz channels. This will cap the MCS number to 150. If for some reason it only uses 1x1 mimo instead of 2x2 you only get 75. Now this is the encoding rate not the actual speed. It ignores all the overhead and very important things like wifi is half duplex. This would be like calling a gigabit ethernet cable 2gbit but ethernet unlike wifi can actually transmit and receive at the same time. You are very lucky to get even 1/2 the MCS value most times it is closer to 1/3

It would be very unexpected to get 100mbps even on the fanciest 2.4g equipment. The numbers you see are mostly lies. Even the very newest stuff that tries to claim over 2gbit wifi rates on 5g generally get 500-600 maximum for most people.
 

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