How to wirelessly use my LG OLED65B7A as a 2nd monitor to my pc laptop running Win10Pro ?

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Hello!

Newbie here!

I have an LG OLED65B7A. It works well enough connected via ethernet cable to my network.

I want to use my LG OLED65B7A as another monitor to my laptop.

I know this can be done using some kind of wireless technology, Miracast, etc.
But do I need to have my LG OLED65B7A connected to my WiFi to set this up?

However, my LG OLED65B7A will not connect to my WiFi even though the WiFi router is just 3 feet away !
I know the WiFi is good: I have several pc's and my cellphone connected.

There is a "SCREEN SHARE" (Miracast) option in the LG OLED65B7A, but when
I select it (using the LG's remote and pressing the input button) this message
pops up:
"The device cannot be connect to your TV.
Please try again. If the issue persists, please restart you TV or
check your device."
So I'm taking this to mean that my pc laptop cannot connect to my LG OLED65B7A ?

More: when I go to the full display of options in the OLED65B7A, and go down to Network,
it tells me the Wi-Fi Connection is "Not Connected.  When I then go into the Wi-Fi
Connection, it tells me,
"Wi-Fi is turned off. Turn it on to see the list of available networks that you can
connect to and additional related menu items."
Again, I know the WiFi is good: I have several pc's and my cellphone connected
to it and they work perfectly.

I've tried manually entering the SSID of my WiFi: the OLED65B7A will not see it, & will not connect.

Any hints?

What am I missing?

I have previously used an HDMI cable from my laptop into an HDMI port
of the OLED65B7A and this works for me to use the TV as a giant monitor
for my pc laptop.

Must I disconnect the wired connection first to get the OLED65B7A connected to WiFi ?

Any suggestions much appreciated!