WordPress Site transfered to another Server. 404 all pages

Too long for a comment, but here is a suggestion. What have you done so far? I recently moved a site successfully like this:

  1. Dump DB
  2. In the Dump, replace every occurence of the old site URL by the new site URL.
  3. Copy over the entire directory
  4. Fit the configuration wp-config.php (DB access, site URL, TLS proxy)
  5. Replay the modified dump in the new database
  6. Load WordPress
  7. Flush all caches, if there are some

Note that points 2 and 4 are crucial.