"Insecure FTP connection" - should I be worried?

It's my job to find ebooks for the wife and put them on her Kindle. Usually, I plug it in to my PC with a USB cable but I had the idea that doing it wirelessly would be a big time saver. Experimenting on my own Kindle, I found that the 'wi-fi sharing' facility of X-plore was superb but, sadly, my good lady has an older Kindle and X-plore is not possible on it.

I've now got portable FileZilla on my PC and have successfully connected to Mrs D's Kindle which has ES File Explorer on it. However, before making the connection I was told by FileZilla that: "This server does not support FTP over TLS. If you continue, your password and files will be sent in clear over the internet."

I swapped ES File Explorer for "File Manager" but still got the same warning. Is it a big deal? Aren't the books I'm transferring from PC to Kindle simply on my own home network as opposed to 'the internet'?

Grateful thanks for any advice.
WinVer 21H2

Long story short, no you shouldn't be worried about transferring files via unencrypted FTP across your LAN if you are using WPA2 WIFI encryption.

I used to FTP from my PC to my Android phone back when older Windows versions required separate drivers to transfer with USB. Windows 10 comes with its own drivers so now I use USB to transfer to my Android phone which is fast on USB 3.1.

If you are concerned about security why not set up Filezilla FTP server on your PC which supports SSL encryption and use an FTP client on your Kindle that supports FTPS/SFTP. I used to transfer with ANDFTP to my PC.

AndFTP (your FTP client) - Apps on Google Play

Many thanks, Clippy. Yes, I've got WPA2, so that's fine. Out of curiosity, I was going to try AndFTP but it's not in the Kindle App store. Since my first post, I've read about Windows' own FTP server which is hiding under Programs & Features/Turn Windows Features On & Off/Internet Information Services. I've ticked every box there but Windows doesn't make a connection. Anyone know if the Windows FTP facility SHOULD work?

That looks very promising, Callender. TYVM indeed!