The “Cannot Find Server or DNS Error” message means one of two things: the user's Internet service is not available or the server in question is currently inaccessible via the Internet.
Why does my iPhone say server Cannot be found?
Checked the internet connection, URL and nothing is wrong with them. But, still, getting a “Safari cannot find server iPhone”. Then, it might be the case that Safari browser is conflicting data from the previous browsing sessions. To fix this issue, you need to clear Safari website data and cache.
Why is Safari saying server Cannot be found?
To fix the issue, you need to clear the cache on Safari: Launch Settings on your iPhone device and choose “Safari”. Then, tap on the “Clear History and Website Data” option. Once done, try to launch Safari to see if the issue has been fixed.