What happened to an old Catflix.su link?
An address can stop opening while a film still exists elsewhere in the catalogue. Begin by searching the title rather than changing random letters in the domain. A link to Aftersun should lead you to the 2022 film, not to a page that happens to have the same word in its address.
Old Catflix.su bookmarks are not a live list of working mirrors. This page does not announce an official replacement domain or claim that every similarly named website belongs to the same operator.
Home opens, but a movie link does not
Return to the homepage, type the name and choose the title with the correct year. The earlier site may have used a different movie address. Save the new title page once you have checked the cast and story. This also helps when a series link points to a season that has moved.
Unblocked access and connection problems
If only one device fails to load the page, test the browser before treating the address as unavailable everywhere. Try a normal browser window and inspect the error message. On a managed school or workplace connection, ask the administrator about access rather than installing an unknown extension.
Keep a bookmark to the Catflix homepage and a backup of My List. Those two simple habits are more useful than collecting a long list of untested mirror names.