Not updated even after 8 hours on WiFi

Try this: https://support.apple.com/en-us/HT201263

I have the same problem. I've installed the iOS 13.6 update on my iPhone 11 and after over 2 hours its still on the progress bar. I've also tried to connect my iPhone 11 to my Mac but It doesn't show up in the "finders" application. Are there anything I can do myself to fix this problem?

Try updating through your computer.

Then I would suggest that you contact Apple directly for help using the contact support link at the top of the page.