(Posting to help others in case that didn't work.)
I had the same issue with Windows 11. I did turn the Wi-Fi to public and it still wouldn't work. I finally turned off my Windows firewall and that allowed the connection.
On reading how to allow Calibre to go through the firewall, I found a page that said how to get programs to be able to have access through the firewall, mainly by adding them to the exceptions. (Here's the link:
https://www.technipages.com/block-un...dows-firewall/ in case you need it.) I didn't see "Calibre" listed, so I tried adding it. The program said it was already there, and it was, but under the "T"s (it is called "The Main Calibre Program" in the firewall list.) Neither the private nor public checkboxes were checked. I checked them both and turned my firewall back on. It seems to still be working.