Mac

App can't see your NAS on macOS 27: no Local Network prompt

An app can't find your NAS, printer, or media server on macOS 27 and never asks for Local Network access. Prove the device is reachable, then fix the permission safely.

Problem summary

If one app cannot find your NAS or printer after updating to macOS 27 and never shows a Local Network prompt, first check whether Finder can reach the device and whether the app appears in System Settings → Privacy & Security → Local Network. Apple says both discovery and direct connections to local addresses can need this permission. Trigger the app's LAN action once, then check the list. An absent app may need a developer fix; beta reports do not establish a bug in the public 27.0 release.

Operator snapshotEvidence first

First proof

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

Screen to open

dns-sd -B _smb._tcp

Expected signal

Finder connects.

Stop boundary

Do not use broad privacy resets or disable SIP.

Layer path

1On macOS, an app needs the Local Network permission before it can browse for or connect to devices on the home network. The system tracks the decision per app, and shows the prompt only when the app first tries to reach the LAN.

2An app that is listed and off has a stored denial; one that is absent may not have made a qualifying network request. Apple documents no macOS reset to the undetermined state, so an absent app needs a real local-network action and, if it stays absent, developer investigation.

3Finder connecting by IP shows that the device and network path work for Finder, but does not prove the other app's exact cause. Local Network privacy also covers direct connections to local addresses, so typing an IP is only a discovery workaround when permission is already granted.

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.

Prove the NAS is reachable

Check: Connect by IP in Finder.

Expected result: Finder connects.

If not: If not, use the network runbook.

Prove discovery works

Check: Run `the "Browse for file shares" command below`.

Expected result: The NAS is listed.

If not: If not, check service advertising and VLAN/mDNS routing.

Check the permission list

Check: Privacy & Security → Local Network.

Expected result: The app is listed and on.

If not: Switch it on, or go to the next step if it is missing.

Make the app ask

Check: Quit, reopen, and scan for devices.

Expected result: The prompt or list entry appears.

If not: If still absent, send the app version and failed action to the developer.

Safe stop: Do not use broad privacy resets or disable SIP.

Fallback and confirm

Check: If access is granted but discovery fails, try the NAS IP in the app, restart the Mac, and recheck.

Expected result: The app still finds the NAS after a restart.

If not: Report the app to its developer; an IP does not bypass permission denial.

Decision tree

If: Finder can't connect to the NAS by IP.

Then: Network reachability problem.

Action: Work VPN, subnet, and firewall in the Mac can't see NAS or printer runbook.

If: Finder connects; the app is listed in Local Network but switched off.

Then: A stored denial.

Action: Switch it on, quit the app fully, and reopen it.

If: Finder connects; the app is not in the Local Network list at all.

Then: macOS has not added the app after a qualifying request.

Action: Reopen it and trigger a LAN action; if still absent, record the exact app version and contact its developer.

Safe stop: TN3179 documents no macOS reset to the undetermined state.

If: Finder connects; the app still can't see the NAS after being allowed.

Then: The app's own discovery or settings are at fault.

Action: If permission is on, try a manual NAS IP to separate discovery from direct access; report continued failure to the developer.

Safe stop: Don't disable System Integrity Protection.

If: Several apps and Finder all lost the NAS at once.

Then: Not a single-app permission.

Action: Check VPN, firewall 'Block all incoming connections', and VLAN placement.

Evidence

Evidence table

Symptom	Evidence to collect	Likely layer	Next action
One app can't find the NAS; Finder can.	Finder connects by IP; `dns-sd -B _smb._tcp` lists the NAS.	App Local Network permission.	Allow the app, or make it ask again.
The app never showed a prompt.	App missing from Privacy & Security → Local Network.	Request never made or not recorded.	Reopen and scan; collect app details for the developer if still missing.
The app is listed but off.	Switch is off in the Local Network list.	Stored denial.	Switch it on and relaunch the app.
Nothing on the Mac sees the NAS.	Finder by IP fails; `dns-sd` lists nothing.	Network, VPN, firewall, or VLAN.	Use the network runbook.

Reference

Commands and settings paths

Browse for file shares

dns-sd -B _smb._tcp

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

Expected: The NAS appears in the live list.

Failure means: Nothing listed can also mean the NAS does not advertise SMB on this network.

Safe next step: Confirm the NAS service and subnet or VLAN configuration.

Test NAS reachability in Finder

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

Where: Finder on the affected Mac, using the NAS address from your router or NAS admin UI.

Expected: Finder mounts the share, proving the device and network path work for Finder.

Failure means: A failure needs a reachability, credential, or NAS service check; it does not diagnose the other app's permission.

Safe next step: Check the NAS SMB service, VPN, subnet, and credentials before changing app privacy settings.

Check Local Network permission

System Settings → Privacy & Security → Local Network

Where: On the affected Mac.

Expected: The app appears and its switch is on after it attempts a LAN action.

Failure means: If absent, macOS has not added it; a generic tccutil reset is not a documented fix.

Safe next step: Record the app build and exact failed action for its developer.

Hardware boundary

Hardware and platform boundary

Change only when

Replace an app only if its developer never adds a Local Network request and it has no manual address option.

Evidence that matters

A DHCP reservation for the NAS so a direct IP address stays valid.
Keeping the Mac and NAS on the same subnet, or mDNS reflection if they are not.

Evidence that does not matter

A new NAS or router — a permission problem is on the Mac.

Avoid

Tools or scripts that reset every privacy permission at once.

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 and Local Network help. The technote says direct local-address connections can require permission and that macOS has no reset to an undetermined app state. Beta reports remain unconfirmed on the shipping 27.0 build.

Sources/assumptions

Assumes a Mac on macOS 27.0 Golden Gate (build 26A428, shipped 2026-09-14), Apple silicon only.
The Local Network permission mechanism is from Apple's technote TN3179 and Apple's Local Network access help page, read 2026-09-15. Apple has not published a macOS 27 change to it.
A silent block without a prompt was reported on macOS 27 betas; it is not confirmed on the shipping build, so this page treats it as unknown.
Apple's TN3179 says Local Network access covers direct local-address connections too and that macOS has no supported way to reset an app's state to undetermined (rechecked 2026-09-18).

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 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.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: macOS 27 Golden Gate is compatible with these computers (HT127255)Used for macOS 27 installing on Apple silicon Macs only (M1 and later); Intel Macs stay on Tahoe. 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 doesn't my app ask for Local Network access on macOS 27?

macOS normally shows the prompt when an app first performs a local-network operation and records the decision. Trigger the app's device scan, then check System Settings → Privacy & Security → Local Network. If it remains absent, collect the app version and failed action for its developer; reinstalling is not a documented reset.

How do I know it's the permission and not my NAS?

Connect to the NAS by IP in Finder (Go → Connect to Server → `smb://<NAS-IP>`). If Finder connects, the device and network path work for Finder; the affected app may have a permission or app-specific issue. If Finder also fails, check reachability first in the Mac can't see NAS or printer runbook.

Can tccutil reset the Local Network permission on macOS?

Apple's TN3179 says there is no way on macOS to reset an app's Local Network privilege to the undetermined state. Use the switch if the app appears in System Settings; otherwise contact the app developer. Do not use broad privacy resets.

Is this a macOS 27 bug?

The Local Network permission existed before macOS 27 and still works the same way on 27. Apps blocked without a prompt were reported on 27 betas, but that is not confirmed on the shipping 27.0 build. Use the steps here, and report the app to its developer if it never asks.