@XxTheZokoxX Yes, I am facing the same issue 3 days ago. This router just purchased 2 months ago, 2.4Ghz not working for ALL devices, only 5Ghz is working well.

Firmware Version:

1.0.0 Build 20191129 Rel. 36545(5553)

Hardware Version:

Archer AX10 v1.20

@XxTheZokoxX 

Same here.

Turned AX1500 to Manual to try manage 2.4Ghz and did some scans and selected channel without users.
Got the utilization to drop and was under impressioneverything is fine.

Nope..

2.4Ghz is piece of s**t with this AX1500. Old Zyxell or mobilephone hotspot works fine with this band. 

Try to up this, because i dont know, before solve this, but again happens me.

@XxTheZokoxX 

@XxTheZokoxX 

I have the exact same issue with my 2.4ghz channel.  I can get 500Mbps down / 20 Mbps up on the 5Ghz channel.  I only get 25Mbps up and 20Mbps down using 2.4Ghz.  I have tried changing channels, channel width, transmit power, etc, nothing helps.  I decided to open up my brand new router and see what was going on inside (maybe the 2.4Ghz antennas were disconnected).  So what I found is that the 5Ghz antenna wires are connected to the mainboard/radio with those tiny micro rf connectors that you see in laptops.  The 2.4Ghz antennas are soldered to surface mount solder pads with gobs of solder.  I wonder if this method of connection is causing the performance drop (the interior conductor is unshielded for about 4mm on each connection).  I even resoldered the antennas to no effect.   Maybe I'll try to add some shielding and see what happens.  Currently, I only have one device (printer) that needs a 2.4ghz connection. 

@Thomwong  I am having the same problem but only when i am using the LAN port. When the PC with LAN cable connect to the router is ON, the 2.4Ghz connection will drop or disconnect. The device with 5Ghz will continue working fine. I just bought the router. Previously I was using the TP Link C1200 and having the same issue. I thought maybe it was because I have been using it for 2 years and got to be replaced. But the problem still exist with the new router. Any suggestion to solve my problem? 

@XxTheZokoxX
Exactly the same problem. Routers drops all the 2.4 GHz connections when it chooses to.

You might think when purchasing such an expensive router it should have basic functionality like 2.4 GHz working. But what you get is a really expensive router which is more unreliable than some 10 $ WiFi Router.

@Kevin_Z 

I had this problem with the only settings changed being password (of course) and Smart Connect disabled. Then I disabled all the fancy features and it still has this problem.