cannot seem to cast

How exactly are you trying to cast to the LG TV?

Your LG TV is a DLNA player. If you are trying to cast from Edge then that would explain it, Edge can only cast to Miracast devices now. The ability to cast to DLNA was removed in the Creators update (1703).

Microsoft developer David R wrote at Feedback-Hub:
“Thanks for providing feedback on Microsoft Edge! We’ve seen feedback that when you choose “cast media to device” from the actions menu, the pane that appears only shows wireless displays, and does not show DLNA devices as expected..... This panel does not show DLNA devices, by design. Some people are seeing the list of wireless displays and believe that DLNA devices are missing due to a bug, when in fact casting to DLNA from Edge is simply not supported any more. We apologize for any confusion this has caused.”

posted Dec 2, 2017 in https://developer.microsoft.com/en-u...sues/11633738/

You should be able to cast to a DLNA device from File Explorer. Right-click on a video (eg. .mp4) and select 'Cast to Device' where your TV should be listed. You can also cast video to a DLNA device from the Films & TV app.

If you are trying to cast by either of those method and it fails to work, are you seeing any error messages?

lafargeotte said:

I can cast from File Explorer. What I would like to do is cast my desktop to the TV, which I cannot seem to do.

I'm sorry to say you (and I) can't cast our desktops. That requires Miracast. Our TVs don't support it, and in my case neither does the PC. There are adapters available that can add Miracast to the TV, such as this...
Microsoft Wireless Display Adapter

Fore more on catinfg the Desktop see these tutorials.

Miracast is a wireless technology your PC, laptop, or tablet can use to project your screen to wireless TVs, projectors, and streaming media players that also support Miracast....

This tutorial will show you how to project your Windows 10 PC screen to a wireless TV, projector, or streaming media player with Miracast.

Connect to Wireless Display with Miracast in Windows 10

Both your Windows 10 computer (PC, laptop, or tablet) and device (TV, projector, or streaming media player) must support Miracast to be able to project your computer's screen to the device.

This tutorial will show you how to check if your Windows 10 PC supports Miracast wireless streaming and screen projection.

Check Miracast Support on Windows 10 PC

lafargeotte said:

If the TV was connected to the network by Ethernet Cable would that help?

No. DLNA uses a network connection, Ethernet or WiFi will do, but Miracast is a wireless connection direct from one device to the other.

Miracast uses Wi-Fi Direct, so the devices don’t even have to be on the same network to communicate with each other.

How-To Geek | How to Use Miracast Screen Mirroring from Windows or Android

More and more new devices are using Wi-Fi Direct. Wi-Fi Direct allows two devices to establish a direct, peer-to-peer Wi-Fi connection without requiring a wireless router. Wi-Fi becomes a way of communicating wirelessly, like Bluetooth.

How-To Geek | What Is Wi-Fi Direct, and How Does It Work?

If I had a USB WiFi dongle for the Desktop PC, would that be any good?

Miracast can be added to a TV with a dongle. WiFi on it's own is not sufficient to add Miracast projection abilities to a PC, the PC's video hardware/driver also has to support Miracast (mine doesn't, but I can use DLNA over WiFi).

Miracast requirements:

• Graphics driver must support Windows Display Driver Model (WDDM) 1.3 with Miracast support
• Wi-Fi driver must support Network Driver Interface Specification (NDIS) 6.30 and Wi-Fi Direct
• Windows 8.1 or Windows 10

Check Miracast Support on Windows 10 PC

It may still work even if your PC hardware doesn't specifically support Miracast, but that's an experiment you'd have to try for yourself (once the TV has Miracast and the PC has WiFi). This is what the Connect app says for my laptop, though I don't have a Miracast TV to test if I would have display problems or not. Direct printing should be no problem though.