@Tito99 Hi Kevin, 

"can it not be detected by all wireless devices at that time even though the web UI and wifi leds shows normal? "

Yes, all show normal.

"Try to adjust the wireless settings of the 5GHz to give it a go, including wireless channel and channel width. You can use channel 36, 40 and 44; channel width 40MHz."

I tried with all configurations and is the same. Only appers after to reset at factory settings, but with the first attemp to connect he asks for the password and then continues trying to connect until the device (smartphone or pc) shows "cant connect" and after dissapears and is not showed in any device, although the leds and web show all normal.

"And please ensure that the firmware is up to date. "

yes, I upgrade to Firmware Version: 3.0.0 0.9.1 v005f.0 Build 170926 Rel.63400n

"when and where did you buy this Archer C3150?"

I bought nov 26, by Amazon to iDeal Sales.

These are the most important things;
1.- After installation and configuration everything went perfectly, 2.4Ghz and 5Ghz
2.- After a few hours the 5Ghz disappeared and the 2.4Ghz one continued to work well.
3.- Then I upgraded the firmware to see if it was fixed but it remained the same.
The 2.4Ghz always kept going well, the problem is that of 5Ghz.
The LEDs turn on for both bands, and the web does not indicate any error.

thanks and best regards

Albert 

@Tito99 I'm seeing a lot of people with the same problem...

https://community.tp-link.com/en/home/forum/topic/175434

@Tito99 Well i've had a learning experience with my C3150. I was running a Cisco with third party Tomato firmware and it worked fantastic but i need more range thus the C3150.

First problem WPS if i try and use it this error is produced. I don't have these encryptions enabled and thus I belive this is a bug.

Error code: 7500
Wireless settings conflict. Please verify the settings, e.g. 1.WEP security or WPA/TKIP encryption is not supported with 11n-only wireless mode enabled; 2.WEP security or WPA/WPA2 Enterprise is not supported when WPS is enabled.

Second if i setup a firewall rule or virtual server say for FTP. I can define the incoming port in this case 21 but not the source IP address. Thus anyone on the internet can try there luck at my server.

It seems TP-Link has made it near imposable to use third party firmware due to the US FCC wanting to stop people winding up the power on there WiFi signal thus I can't get or even buy any third party firmware for this unit and it appears TP-Link have no intention of updating it or fixing bugs.

It's a pity the harware platform appears good but the firmware is a let down.

Michael