Backing up to local storage, or through ethernet has worked, but when backing up via WiFi it routinely comes up with the "Time Machine needs to recreate your backup" message.
Furthermore Time Machine insisted (probably still does) on using the deprecated AFP protocol that even Apple no longer maintains.
A backup that cannot be trusted is not a backup, so years ago i switched to Arq Backup (https://www.arqbackup.com/) instead. While not as "polished" as Time Machine (Restore functionality could _really_ use some work) it actually works, and in all my years of using it, i have never experienced a failed repository.