What exactly is needed to run Time Machine against a NAS on MACOS26?

Ideally, choose an NAS that offers turnkey support for Time Machine out of the box, both Synology (setup instructions) and QNAP (setup instructions) do so. Technically, you can stand up a Time Machine server in other ways (including using a Mac as a TM server), but an NAS is arguably the most straightforward way to set up network Time Machine backups. 

Personally, I use a Synology DS223j with a pair of 10 TB HDDs installed to back up 5 Macs in the house with Time Machine (separate shared folder for each Mac sized at ~2.5x the internal storage), with the remaining space used as general file storage for everyone in the house. Working fine with Tahoe.

I have a similar problem with the LS220 - similar research led me to the same conclusion that the LS220 doesn't support SMB v3.0 so can't be used as a Time Machine backup.

it’s not SMB3 per se, it is what came along with it on the server side. In order to host a time machine server, it must support the “Time Machine over SMB“ specification.

In the case of Samba, the open source SMB server many NAS use, support for that specification arrived at the same time as support for SMB 3.

Here is the latest post on the Buffalo support website:

As of September 15th 2025, with the release of MacOS 26 Tahoe, Apple has deployed step 1 of 2 towards the removal Time Machine over AFP protocol functionality. With this major release version of MacOS (26), only Existing Time Machine over AFP configurations will continue to function; it has been disclosed that in the next release, step 2, will completely remove Time Machine over AFP functionality.

Model Series Compatibility

LS700: Fully compatible with MacOS 26 Time Machine

TS3030/5020/71210: Fully compatible with MacOS 26 Time Machine

LS200: Not Compatible with MacOS 26 Time Machine, Firmware update Investigation in progress

TS3010/TS3020/TS5010/TS6000: Not Compatible with MacOS 26 Time Machine, Firmware update Investigation in progress

LS400/LS500: No firmware update is planned, will continue to work with MacOS 15.x or older

TS1000/TS3000/TS5000: No firmware update is planned, will continue to work with MacOS 15.x or older

Older/Unlisted: No firmware update is planned, will continue to work with MacOS 15.x or older

I have a similar problem with the LS220 - similar research led me to the same conclusion that the LS220 doesn't support SMB v3.0 so can't be used as a Time Machine backup. I think that although Apple hasn't deprecated AFP with Tahoe -- it won't let you set up a new Time Machine destination with AFP. At least, I can't get the Time Machine "Add New Drive" setting to recognise the LS220.

I set up the NAS with SMB, following the instructions from Synology. That was a bit over 3 years ago, IIRC.

Sounds like the issue is on the Buffalo side, good they at least acknowledge it.

After Tahoe was released, my Time Machine backups repeatedly failed. In trying to rebuild them, I managed to destroy my inactive backups and couldn’t restart new ones. After realizing this is a widespread issue with no estimated time for a firmware update to fix it, I decided to go with a new system. My first choice was to go with Synology but was disappointed with the complaints over their recent restrictions on supported disk drives; I have no desire to get myself locked into another ecosystem. I purchased a 4 bay Terramaster instead. After installing 4 terabyte hard dives and a 500 gigabyte SSD to hold the TOS, much more that I’d ever need, I rebuilt my backups. I’ve been satisfied ever since. Now that I have a full featured NAS on my system, I’m looking over its capabilities over simple backups and wondering if any can help with my current use cases.

Carlos da Roza wrote:

I had purchased a Buffalo LinkStation LS220 NAS to replace my Time Capsule since Apple had deprecated AFP with Tahoe.

That's not correct.

In my case I did research the LS220 and it claimed it had full support for Time Machine (yes 2 years ago) and I set it up and it worked fine. Then I updated to Sequoia and got these messages "This disk is not recommended for backups..."

OK I thought I'd set it up to do Time Machine on SMB -- but you can't do that (not a Mac problem, rather the "NAS Navigator 2" software, the Buffalo admin software, will not allow it.

I wrote to Buffalo support and like others here they said we will fix this but they didn't say when. I'm on the latest firmware (just updated recently) and still no fix.

It's not that it never worked, it used to work. Apple changed (years ago now) and Buffalo has not updated.