Mac

Mac can't see NAS or printer after Tahoe or macOS 27 update

Check Local Network permission, Bonjour discovery, VPN routing, and direct reachability when a NAS or printer disappears after a macOS update.

Start here: Grant the permission

Privacy & Security → Local Network → toggle the failing app ON.

Problem summary

If a NAS or printer disappears after a macOS update, separate device reachability from Bonjour discovery and per-app Local Network permission. Check the app's switch in System Settings, connect by IP from Finder to test the device, then compare discovery with `dns-sd`. A direct IP can bypass a discovery failure, but Apple says it does not bypass a denied Local Network permission for the affected app.

Operator snapshotEvidence first

First proof

Open Privacy & Security → Local Network and check the app's toggle.

Screen to open

dns-sd -B _smb._tcp

Expected signal

The app that can't find devices is listed and ON.

Stop boundary

Disabling the firewall entirely instead of just the 'block all incoming' option.

Layer path

1Seeing a NAS or printer through Bonjour is distinct from reaching it by IP. Finder-by-IP and `dns-sd` are separate tests; a direct address can bypass discovery but not a Local Network permission denied to the affected app.

2Modern macOS tracks Local Network access per app. A switched-off entry is evidence of a denial; an app absent from the list may not have made a qualifying request. A preceding update does not prove the permission changed.

3Two environmental factors mask discovery: a full-tunnel VPN that routes LAN traffic away (device unreachable), and different subnets/VLANs where mDNS doesn't cross without a reflector (device reachable by IP but never discovered). Naming reachable-vs-discoverable and same-subnet-vs-not points straight at the fix.

Runbook

Step-by-step runbook

Start here. Do each check in order, compare it to the expected result, and stop when the evidence explains the failure or the safe stop point applies.

Grant the permission

Check: Privacy & Security → Local Network → toggle the failing app ON.

Expected result: The app can issue mDNS queries again.

If not: If the app isn't listed, relaunch it and trigger discovery to prompt.

Prove reachability

Check: Connect by IP with `smb://<NAS-IP>` and add the printer by IP.

Expected result: You confirm the device is reachable and get working access now.

If not: If IP fails, switch to the reachability branch (VPN/subnet/NAS).

Clear network blockers

Check: Disconnect a full-tunnel VPN; turn off firewall 'Block all incoming'.

Expected result: LAN traffic and discovery responses are no longer suppressed.

If not: If devices are cross-subnet, plan mDNS reflection or keep using IP.

Verify discovery system-wide

Check: Run `the "Browse for SMB file shares via Bonjour" command below` / `_ipp._tcp`.

Expected result: Devices appear, confirming mDNS works at the OS level.

If not: If they appear here but not in an app, check its permission and configuration.

Re-test and settle

Check: Relaunch the app / reopen Finder's Network section.

Expected result: Devices are visible and connect without an IP.

If not: If discovery still fails, try a manual address only when the affected app has Local Network access.

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Decision tree

If: Connect-by-IP works but the app/Finder can't discover the device.

Then: Device reachability works for Finder; the app may have a permission, discovery, or configuration failure.

Action: Check the app's Local Network switch and compare `dns-sd` before changing anything else.

If: Even connect-by-IP fails and a full-tunnel VPN is active.

Then: The VPN is routing LAN traffic away from the local network.

Action: Disconnect the VPN or enable local-LAN/split-tunnel access, then retry.

If: Connect-by-IP fails, no VPN, device on a different subnet/VLAN.

Then: mDNS can't cross subnets and routing may be blocked between VLANs.

Action: Use IP directly, and enable mDNS reflection/repeater on the router if cross-subnet discovery is needed.

If: `dns-sd` shows nothing and firewall 'Block all incoming' is on.

Then: The firewall is suppressing discovery responses.

Action: Turn off 'Block all incoming connections' (keep the firewall on otherwise) and retest.

If: No client (not just this Mac) can reach the NAS/printer.

Then: The device's service is off (SMB disabled, printer offline) — not a Mac problem.

Action: Fix the NAS share/printer service; confirm the device is healthy.

Evidence

Evidence table

Symptom	Evidence to collect	Likely layer	Next action
NAS/printer vanished right after the Tahoe update.	Privacy & Security → Local Network shows the app off/missing.	A switch that is off is a denial; absence is not proof of an update reset.	Toggle a listed app on; if absent, trigger its LAN action and collect details for its developer.
App can't discover, but `smb://<IP>` connects.	Connect-by-IP succeeds; `dns-sd` works system-wide.	Finder reachability works; affected app needs separate diagnosis.	Check the app's Local Network switch, manual address option, and own settings.
Nothing local is reachable while VPN is on.	Disconnecting the VPN restores access.	Full-tunnel VPN routing LAN traffic away.	Enable local-LAN access / split-tunnel, or disconnect.
Device on guest/IoT VLAN never appears.	Same device reachable by IP from the Mac's subnet only via routing.	Cross-subnet mDNS not reflected.	Connect by IP; enable mDNS reflection on the router.
`dns-sd` lists nothing for any service.	Firewall 'Block all incoming connections' is enabled.	Firewall suppressing discovery.	Disable that single option; keep the firewall on.

Reference

Commands and settings paths

Browse for SMB file shares via Bonjour

dns-sd -B _smb._tcp

Where: Terminal on the Mac (Ctrl-C to stop).

Expected: Lists NAS/file-share services as they're discovered on the LAN.

Failure means: Nothing appears if the service is not advertising or mDNS cannot reach it.

Safe next step: If Terminal can discover it, test the affected app's permission and own settings.

Browse for network printers via Bonjour

dns-sd -B _ipp._tcp

Where: Terminal on the Mac (Ctrl-C to stop).

Expected: Lists AirPrint/IPP printers as they advertise themselves.

Failure means: Empty list means the printer isn't advertising or mDNS is blocked.

Safe next step: Add the printer by IP as a robust fallback.

Connect to the NAS by address (discovery bypass)

Finder → Go → Connect to Server → smb://<NAS-IP>

Where: Finder on the Mac.

Expected: Mounts the share in Finder, proving that Finder can reach the NAS without browsing.

Failure means: If this fails too, investigate VPN, subnet, firewall, and NAS service first.

Safe next step: If it works, check the affected app's permission and discovery separately; direct IP does not bypass a denial.

Resolve a specific advertised service

dns-sd -L <ServiceName> _smb._tcp local

Where: Terminal on the Mac, using a name from the browse list.

Expected: Shows the host and port behind a discovered service.

Failure means: If it can't resolve, the advertisement is incomplete or stale.

Safe next step: Connect by IP and check the device's service configuration.

Hardware boundary

Hardware and platform boundary

Change only when

Enable mDNS reflection (Avahi reflector or your router/UniFi's mDNS option) if you deliberately keep NAS/printers on a separate VLAN and want cross-subnet discovery.
Set static IPs or DHCP reservations for the NAS and printer so the connect-by-IP fallback stays stable and you don't depend on discovery.

Evidence that matters

A router that supports mDNS reflection/repeater across VLANs if you segment your network.
Stable device addressing (reservations) so manual connect-by-IP is reliable.
Devices that correctly advertise their services (SMB, AirPrint/IPP) on the same subnet as the Mac.

Evidence that does not matter

Reinstalling printer drivers before isolating permission, discovery, and reachability.
The Mac's Wi-Fi generation — discovery is a permission/mDNS issue, not bandwidth.
Factory-resetting the NAS before checking the Local Network permission.

Avoid

Disabling the firewall entirely instead of just the 'block all incoming' option.
Leaving a full-tunnel VPN on and concluding the device is broken.
Relying on Bonjour discovery across VLANs without a reflector — use IP instead.

The Local Network permission list

Reference images and diagrams. Click any image to view full resolution.

macOS System Settings, Privacy and Security, Local Network, showing the per-app permission list with enabled toggles; the app names and icons are blurred for privacy. — Privacy & Security → Local Network shows per-app access decisions. App names blurred for privacy. First-party screenshot (macOS Tahoe 26.5).

Related tool/checklist

Use the linked tool when you need a guided plan from your exact symptoms instead of a static checklist.

NAS setup planner

Last reviewed

2026-09-18 · Reviewed by HomeTechOps. Rechecked 2026-09-18 against Apple's TN3179. Separates Finder reachability, Bonjour discovery, and the affected app's own permission. Direct IP is conditional on permission and an update is not treated as proof that a grant reset.

Sources/assumptions

Applies to Tahoe and macOS 27; Local Network privacy is per-app, and a temporal link to an update alone does not prove a reset of permission (rechecked 2026-09-18).
Discovery uses Bonjour/mDNS; cross-subnet/VLAN discovery requires mDNS reflection on the network, which is outside the Mac's control.
Commands (`dns-sd`, Connect to Server) follow Apple's documented behaviour; NAS/printer menu labels vary by vendor.
macOS 27.0 Golden Gate (build 26A428) shipped 2026-09-14 and installs on Apple silicon Macs only — Intel Macs stay on Tahoe. The diagnostic sequence on this page is unchanged. Named Tahoe point-release bugs are tagged still-applies / Tahoe-only / unknown, and Time Machine over AFP no longer works on 27 (checked 2026-09-15).

Source-backed checks

HomeTechOps turns official docs and conservative safety rules into a shorter runbook. These links are the source trail for the page direction.

Apple Support: Control access to your local network on MacUsed for the Local Network privacy permission — apps must be granted Local Network access in Privacy & Security before they can discover NAS, printers, and other devices via Bonjour/mDNS; the grant can reset across macOS updates.Apple Support: Solve internet connection problems on MacUsed for the built-in Network settings diagnostics, renewing DHCP, and the order Apple recommends for isolating a Mac-side vs router-side networking fault.Apple Support: Recommended settings for Wi-Fi routers and access pointsUsed for router security, band, naming, and access-point settings that affect mixed home devices.Apple Developer: TN3179 Understanding local network privacyUsed for how the Local Network permission gates an app's Bonjour browsing and connections to local addresses on a per-app basis. Verified 2026-09-15.

Diagnostic rule

1. Check the simplest signal first.
2. Change one thing at a time.
3. Avoid unsafe electrical or data-loss steps.
4. Stop when the evidence says the risk moved.

FAQ

Why can't my Mac see my NAS or printer after the Tahoe update?

Check System Settings → Privacy & Security → Local Network for the affected app, then test Finder by IP and Bonjour discovery. A switched-off app permission is one possible cause; a VPN, service outage, or different VLAN can look similar. An update alone does not prove the permission was reset.

How do I connect to my NAS if it won't show up in Finder?

Connect by address in Finder: Go → Connect to Server → `smb://192.168.1.50` (your NAS's IP). For a printer, use Printers & Scanners → Add → IP. If Finder connects, the device and path work for Finder; the affected app may still have a permission or configuration problem. Direct IP does not bypass a denied Local Network permission for that app.

Could my VPN be hiding my NAS and printer?

Yes. A full-tunnel VPN routes all traffic — including your local network — through the tunnel, so LAN devices become unreachable. Disconnect the VPN and retry; if that's it, enable 'allow local network access' (split-tunnel) in the VPN client or exclude your local subnet.

How do I check if Bonjour discovery is working on my Mac?

Run `dns-sd -B _smb._tcp` in Terminal for file shares (or `_ipp._tcp` for printers). Your devices should appear in the live browse list. If they do but an app still can't see them, that app is missing the Local Network permission. If nothing appears, mDNS is blocked or the devices are on a different subnet/VLAN.

Does this page apply to macOS 27 (Golden Gate)?

Yes. macOS 27 installs only on Apple silicon; Intel Macs stay on Tahoe. Check Finder-by-IP reachability, Bonjour discovery, and the affected app's Local Network switch separately. An app missing from the list was reported on 27 betas but is not a confirmed public-release regression; see no Local Network prompt on macOS 27. A Finder connection by IP tests Finder's path, not the other app's permission.

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