@Kevin_Z 

correct 2.4G is not stable, but the 5G is stable. 

Have manually changed channels to less crowded, have narrowed them, have disabled the AP 2.4 hoping the Router 2.4 would stay on but that didn't work either. There routers are only a few weeks old, worked fine with all 4 channels nicely covering the house the first few days, but now not reliable. Did not have any issues like this w/ my previous router which makes me think it is unlikely environmental interference and closely matches other people's problems that eventually result in warranty / replacement. Shame, I loved these routers the first few days and thought I'd be set. 

I've battled missing 2.4 GHz on my TP-Link AX55 AX3000 router for years now.  I spend the last 2 solid days working with it and was amazed to find out that the problem completely disappeared when I removed the 32GB USB drive from the router and re-booted.  Hopefully this will work for others......

  @r4zorxt

I have been facing the same issue for the last few days. It started after I changed my internet provider and they gave a different WiFi modem. The coverage was bad so I started using the TPLINK Archer C5 as the WiFi network after converting it into an access point. So the 5G works great but 2.4G somehow has better coverage in certain parts, most importantly the bathroom 😂 So I tried all the hacks, changing the channel, channel width, transmit power. But nothing worked. My devices wouldn't connect even though the network was showing. I actually came to this thread, looking for answers just like a few minutes ago and looking at how this issue is so common and most often unresolved using the common methods I wondered what are we missing. Now I am not sure if this will work for everybody but I think this is the miracle fix for everyone who has tried all other things.

We often tend to keep the same password for both 2.4g & 5G bands. Well all I did was to change the password for 2.4G to a different one and voila it connected and started working. So guys lemme know if it worked.

@Kevin_Z

My Tp-Link Acher Ax73 v1.0 router suddely lost the 2.4 ghz connection but 5G is working fine( if i turn on ), checked the setting as 2.4 is turn on but the wifi light never show.

things i tried on setting

- change width ( 20 or 40 )

- change channel ( auto, 1, 6, 10, 11 )

- change 2.4 and 5g password and SSID

- updating firmware - 1.3.5 build 20230922 rel.71211(5553)

- changing mode 802.11b/g/n/ax mixed

- security change WPA2-PSK[AES] / WPA3-PSK[AES]

noting seem working, wifi light still off without turning the 5g on, so what should i do now ? thinking about factor reset but saw post some people have remind the same issus trying it, isit possible my 2.4ghz somehow fried ?