Using Asus now.

Not the best, but anything is better than TP-Link.

Mine is on the corner. Guess I'll burn it and post on YouTube.

@PlastiBots 

Ok.. so I tried the following and so far it's stable.  First of all, I sat for 1 hr fidding with changing channels and channel width for both 2.4 and 5, and tried saving without reboots.  Sometimes it worked, but it failed soon after.   So far here's what's working for the moment.  I am not super confident of this yet as I did a system reboot as well after making these changes.  I suspect the reboot just reset the BS that will likely come back.  Will report back if it does:

2.4GHz: Security WPA2/3 personal, Version:Auto, mode n/ac/ax mixed, channel width 20MHz, Channel 10, Transmit High.  

5GHz:  Security WPA2/3 personal, Version:Auto, mode n/ac/ax mixed, channel width 40MHz, Channel 157 (this was the default), Transmit High.  

@PlastiBots 

Good to hear that the workaround works for you too. Hope TP Link to provide a new firmware to fix this issue.

@nkbm 

So, after >12 hrs it's more stable, but we have had a few disconnects of phones from 2.4, so not in the clear yet. Also, want to point out that all was fine for 3-4 days without issue, then this issue came out of nowhere...  I feel that the reboot fixed it rather than the changes I noted earlier.   Also, I noticed something else odd with parental controls for my sons phone.   In the middle of all this, he complained as his phone was blocked at 5PM (even though the control was from 11PM - 7AM).   There's another thread on this, but apparently there's a bug around the time and DST etc..  In my case, the router showed the right time. Only after I removed and re-added his parental control profile, did it let him back in.  So, yeah, more bugs.  Not impressed for a $400 CAD router!  Im leaning on returning this for another brand, but going to give it a few more days.  

TP-Link, you need to acknowlege these issues and address them. It's a shame that this has been going on so long and there's been nothing in terms of fixes for this.  

IMHO,

It's the chip degradation, TP-Link doesn't have a solution to all our cases with "2.4 lost" rather than to replace unit to another (till a warranty is valid). Don't expect to get a firmware fix, choose another Brand (as I did)

An update on the changes I noted earlier:  My family has witnessed a number of droped wifi connections to 2.4 - a few times each day.  At times it requires re-entering the WiFi password. Not acceptable.   So yeah, likely returning this router...

@PlastiBots   Just ordered the Asus RT-AX86U. Some great reviews and looks like it's a stable device.    TP Link going back after I get it.

@Danize 

I had this issue and the reason the 2.4 Ghz band disappeared was because I had plugged in a USB 3.0 HDD that was placed too close to the router. (I had it sitting 2 inches away from the antenna)

Apparently, USB 3.0 ends can cause 2.4 Ghz interference.  This was also worse for me because I used a USB 3.0 extender which is probably not shielded very well.

Good luck!

@Kevin_Z ,

People, I am testing anymore and find strange behavor, I can see 5(Five!) SSID´s when I have only 3! configured. Officially I configured only:

TP-LINK_DF7924 -> My main SSID -> 2.4Ghz

TP-LINK_DF7924 -> My main SSID -> 5Ghz

CCATHARINA -> Guest SSID -> Only 2.4Ghz

But!

It is as if the SSID´s of the main network are doubling the signal of the network but without a name. Signal for Guest Network maybe right.

Does this have any logic to be like this?

Thank´s