The message that usually starts this whole thing is short and unhelpful: "You can't connect to the file share because it's not secure." Windows throws that at people the moment they try to reach an old NAS share, and it never explains what changed.
What changed is the protocol version. Your NAS and your PC are arguing about which dialect of SMB to speak, and one side refuses to use the old one anymore.
I have untangled this on Synology, QNAP, and a couple of ancient WD boxes, and the fix is almost always the same underlying decision: SMB1 or SMB3. So let me lay out what actually separates them, why every vendor turned SMB1 off, and what to do when an old printer or camera still needs it.
What SMB actually is, in plain terms
SMB stands for Server Message Block. It is the language Windows, macOS, and your NAS use to share folders over the network, the thing that makes NASMovies show up like a local drive.
The version numbers matter because each one is a different generation of that language. SMB1 dates to the late 1980s and was polished up in the Windows XP era. SMB3 arrived with Windows 8 and Windows Server 2012 and is what everything modern speaks.
There is no SMB2 to worry about on your NAS, really. SMB2 and SMB3 share the same modern core, so when people say "SMB3" they usually mean the whole modern family, and "SMB1" means the old outlier that got left behind.
The security gap is the whole story
The first time I hit this, I assumed the vendors disabled SMB1 to be annoying. They did not. SMB1 has no meaningful encryption, no protection against tampering, and it happily trusts whatever answers first on the network.
That last part is what made WannaCry spread across the planet in 2017. The ransomware used an SMB1 flaw called EternalBlue to jump machine to machine with no clicking required. After that, Microsoft started removing SMB1 from fresh Windows installs, and NAS makers followed fast.
SMB3 closed those holes. It adds AES encryption you can turn on per share, signing so a man in the middle cannot quietly alter your files in transit, and pre-authentication integrity checks that stop an attacker from downgrading you back to the weak protocol.
Speed and features, side by side
Security aside, SMB3 is simply a better performer. SMB1 sends lots of small chatty round trips, which crushes throughput on anything but a fast local link. Copy a folder of thousands of tiny files over SMB1 and you can feel it crawl.
SMB3 supports larger reads and writes, multichannel (using two network links at once), and smarter caching. On a gigabit connection the practical difference on big transfers can be the gap between saturating the line at around 110 MB/s and stalling at half that.
| Feature | SMB1 | SMB3 |
|---|---|---|
| First shipped | Late 1980s, refined for Windows XP | Windows 8 / Server 2012 |
| Encryption | None | AES-128 / AES-256, per share |
| Signing / tamper protection | Weak, easily bypassed | Mandatory pre-auth integrity |
| Large file speed | Slow, chatty round trips | Large reads, multichannel |
| Known major exploit | EternalBlue (WannaCry) | None of that class |
| Default on modern NAS | Disabled | Enabled |
Put bluntly, there is no category where SMB1 wins on merit. Its only remaining job is talking to hardware too old to know anything newer.
So why would anyone still touch SMB1
Compatibility, and nothing else. A short list of gear that often speaks only SMB1: Windows XP and Vista machines, some Windows 7 boxes that were never updated, older network scanners and copiers that "scan to folder," a few IP cameras, and cheap smart TVs and media players from the early 2010s.
A mistake I see constantly is someone blaming the NAS when a $90 office scanner is the real holdout. The scanner was built in 2013, its firmware speaks SMB1, and it will never get an update. The NAS is fine.
When you truly cannot replace the old device, the move is not to weaken the whole NAS. It is to isolate the problem, which I will cover below.
Reading the errors you will actually see
The exact wording depends on your operating system, but a few show up over and over. On Windows you get "You can't connect to the file share because it's not secure. This share requires the obsolete SMB1 protocol."
On macOS the failure is quieter, usually just a spinning connect that times out, or "There was a problem connecting to the server." Older Linux with a recent Samba client will say the negotiated protocol is unsupported.
All three mean the same thing. One side offered only SMB1, the other side refuses SMB1, and there is no common version left to agree on.
How to move to SMB3 the right way
On most NAS boxes this is a menu, not a command line. The wording differs but the location is similar across brands.
- Open your file services settings. On Synology this is Control Panel, then File Services, then the SMB tab. On QNAP it is Control Panel, then Network and File Services, then Win/Mac/NFS.
- Find the protocol range. Look for "Minimum SMB protocol" and "Maximum SMB protocol" (Synology calls it exactly that under Advanced Settings).
- Set the minimum to SMB2 and the maximum to SMB3. This blocks the insecure old version while letting every modern client connect at the best level it supports.
- Leave SMB1 disabled. If there is a separate "Enable SMB1" checkbox, keep it unchecked.
- Update your clients. A fully patched Windows 10 or 11 machine already prefers SMB3, so nothing to do there. Old Windows 7 needs to be current, or retired.
After you save, reconnect the share by its name or IP. If it maps cleanly, you are on SMB3 and done.
Handling the one device that refuses to move
Say the scanner genuinely needs SMB1 and replacing it is not happening this quarter. You still do not flip SMB1 on for the main NAS.
The safer pattern is to put that one legacy device on its own isolated network segment or VLAN, keep it off the internet entirely, and if possible give it a dedicated share that holds nothing sensitive. Some people run a tiny separate old NAS just for that one job and keep it powered off until scan day.
Where this leaves you
For any home NAS in 2026, the answer is not close. Run SMB3, keep SMB1 off, set your minimum protocol to SMB2 so nothing sneaks in under it, and let modern clients negotiate up from there.
If a single old gadget still needs SMB1, cage it on its own segment rather than lowering the drawbridge for the whole house. The old scanner can have its walled garden while the rest of your storage stays fast and encrypted. For a deeper read on the protocol's history and the versions in between, the Server Message Block overview is worth ten minutes.
Frequently asked questions
Is SMB2 the same as SMB3 for my NAS?
For everyday use they behave the same way and share the same secure core, which is why NAS settings often group them together. SMB3 adds per-share encryption and multichannel on top of SMB2. Setting your minimum to SMB2 and maximum to SMB3 covers you either way.
Why did my Synology or QNAP stop letting old devices connect?
A firmware update raised the minimum SMB protocol to block SMB1 for security. The old device only speaks SMB1, so there is no common version to negotiate. You can either replace or update the device, or isolate it and enable SMB1 only for that one case.
How do I check which SMB version I am actually using?
On Windows, open PowerShell and run Get-SmbConnection. The Dialect column shows the negotiated version, such as 3.1.1 for modern SMB3 or 1.5 for SMB1. On a NAS the current protocol range is listed in the SMB or file services settings.
Is it ever safe to turn SMB1 back on?
Only as a narrow, temporary exception for a single legacy device that you keep off the internet and on an isolated network segment. Enabling it globally reopens the exact flaw WannaCry exploited. Treat it as a last resort, not a normal setting.
Will switching to SMB3 make file transfers faster?
Often yes, especially with lots of small files or large single files over a gigabit link. SMB1 uses chatty round trips that waste bandwidth, while SMB3 supports larger reads, writes, and multichannel. On a good gigabit setup you can approach 110 MB/s where SMB1 might stall at half that.
