@ravi_t  your C6 is V2 or V3.20?

@Kevin_Z It's the EU version. I installed your beta build and it bricked the router. I was able to recover it. The current version is 1.3.6 Build 20200902 rel.65591(4555). Hardware version is Archer C6 V2.0.

You think i should try to install the beta build again?

 Was a solution for this ever found?

I just Googled on issues surrounding 2.4 GHZ not working on TP-LINK.  I live in Italy and have to use a modem/router.  I have been using the TP-LINK model TD-W8970 which works on the 2.4GHZ and has been very reliable.  I wanted to upgrade my system mainly to increase the signal strength in the house with WiFi extenders.  So I bought the TP-LINK AC 1200 (model Archer VR400) and bought two extenders AC 1200.  The AC 1200 has both the 2.4 GHZ and the 5 GHZ.  The 5 GHZ works fine, no issues.  On the initial set up, it took me forever to get the 2.4 GHZ to transmit, even though it shows on the router that it is broadcasting and it has been enabled on the setup.  So once I got it working, the extenders synced and it was reliable.  Had the power in the building go off and I have not been able to get the 2.4 GHZ back - no matter how much resetting/rebooting and messing around with it I do.  Again, no issues with the 5 GHZ.  So I thought I must have a defective unit, so I bought another AC 1200 modem/router and same issue, cannot get the 2.4 GHZ to work.  The replacement one that I bought,  the box had been open, but the salesman told me I could bring it back if there is a problem.  My feeling is that who had it before me had issues with the 2.4 GHZ also. So I am back on the old TD-W8970 where the 2.4 GHZ (does not have 5 GHZ) works fines, and will be taking back the two AC 1200 modem/routers and the two AC 1200 WiFi extenders unless there is a solution out there.  Any help? 

I have Archer C7 v2 FW: 3.15.3 Build 180114 Rel.39265n when I shut down my PC, the 2.4ghz stopped working..however 5ghz works fine. I tried reboot router and change channels.. still nothing.. in order to fix this issue, I had to turn on the PC..once I loaded into windows, 2.4ghz works again. Does anyone know why?

Thanks

I have been experiencing the same issue with this model Archer Mr6400 ! I always connect to 5Ghz, but my other devices is connected with 2.4GHz only. Now all devices is not responding i checked its 2.4ghz wireless is not showing done resetting changed channels but still facing same issue 

@Kevin_Z 

I have the same issue. 2.4 ghz network drops out. But my device is the TP-Link Archer C5400 v2.0. I'm in the process of doing an exchange. Someone might want to think about applying the fix for the AX6000 or whatever to the C5400 as well. This just all of a sudden started happening even worse a couple days ago - January 21, 2021. Not good for a 1.5 year old wireless router. It also concerns me that its not for sale anymore on your website, that I could tell.