why is my ipad mini Generation 6 showing many web sites as not supported

Some websites may incorrectly identify your iOS/iPadOS Safari User Agent when used in one or other of its browsing modes - of which their are two - these being Desktop and Mobile. When operating in Desktopmode, the User Agent will declare itself as Mac computer; in Mobile, the browser will appear to be iPadOS.

It’s easy to switch between modes if a website isn’t functioning correctly. From the desired web-page, touch the aA icon at the left of the Address Bar; this will reveal a menu. From the menu select Website Settings, then select (or deselect) Request Desktop Website, then tap Done. Now refresh the webpage.

The chosen setting will be saved for the selected website - and can be simply reversed if needed.

Hi Holjon,

Thank you for participating in the Apple Support Communities. If you are not able to open websites on your iPad, here are a few steps to try to see if its helps:

1. Try using another strong Wi-Fi connection to see if this could be a factor.
2. Once you have connected to a strong internet connection, restart your device to see if the refresh resolves the issue.
3. Clear your website data by following the steps here and see if the issue persists: If Safari isn't loading websites or quits on your iPhone, iPad, or iPod touch - Apple Support

Have a great day.

You are very welcome. I presume your issue is thus resolved.