I am a linux newbie. I have recently installed manjaro KDE. I have a TP-Link 823WN V3. But it is not working. It shows the wifi networks but I cannot connect to them.
Welcome to the Manjaro forum. If you hope to get any technical assistance here it would be helpful if you would post some information about your system. Please read:
You have to install
8192eu-dkms from AUR together with linux-headers for you running kernel, and then add in a file, for example
/etc/modprobe.d/wifi_fix.conf the line
Once you reboot you should have wifi working.