Tahoe and Time Machine not working at all over wifi.

I upgraded three Macs the other day with Tahoe (two new Mac minis and my MacBook Pro m4). I use Time Machine to back up all three to a Synology NAS 1522+. It has been working flawlessly for years on various Apple computers. All three will no longer back up to the NAS. In fact, over the Wi-Fi, it refuses to see the volumes.

I thought it was a volume version thing (all computers used Sequoia to make the original backups), but after connecting my MacBook to the network with Ethernet, it saw the volumes. I started the backup again, but it soon failed, corrupting my backup. I tried the same with my new Mac mini (which is always hard-wired), and it also failed. I started a new backup, but it also failed.

I talked with Apple support for a few hours and they concluded that a problem with Tahoe and SMB is the issue. I was put on a list to get the fix ASAP.

I transferred 2 TB of data from an SSD to the NAS (ran all night) to free up the SSD so I can use it as a backup device. Hopefully THAT will work with Time machine. The drag and drop copy worked fine.

My recommendation is to not use Time machine to backup your files for now with any NAS. You could corrupt your existing time machine backups.

Apple has to fix this and SOON! I have 8 TB of critical buisiness date on my NAS. I did not follow my own recommendation to NOT install the latest OS version from Apple until it has fully tested, as Apple does not seem to do a good job of testing everything and relies on users like you and me. Time Machine is a critical piece of software. They should have tested this first!

In conclusion: Time will not be reliable using WIFI to backup to a NAS or even see the existing time Machine volumes on the NAS. Time machine is not reliable even when using Ethernet and hard wired to your NAS.