When a NAS is not detected on the network, possible causes include power or hardware faults, physical network faults, discovery or firewall settings, IP configuration problems, and network segmentation. Each of these has a clear fix. This guide works through each in order of frequency, with exact steps for both Synology and QNAP NAS devices.
In short: First verify the NAS is powered on and verify the LAN indicators against the NAS model’s hardware guide; a link/activity indicator may remain lit for link and blink during traffic. Then confirm the NAS and your computer are on the same network (same 192.168.x.x subnet). Then use the vendor discovery tool (Synology Assistant or QNAP Qfinder Pro) rather than Windows file browsing - those tools use local discovery mechanisms, but automatic discovery generally requires the computer and NAS to be on the same subnet and the relevant firewall traffic to be allowed. If the discovery tool finds it, you have a Windows-side problem, not a NAS problem.
Step 1: Confirm the NAS Is Powered On and Connected
Before diagnosing network issues, confirm the basics. Check the NAS's power LED - it should be solid green or blue depending on the model. The network LED on the back of the NAS (next to the Ethernet port) should also be lit and blinking with network activity. If the expected link indicator is off, consult the model’s hardware guide and test the cable, router or switch port, and NAS network port. If the power LED is amber or red, the NAS has a hardware warning - check the NAS's own display or beep code.
Ensure the Ethernet cable runs from the NAS directly to your router or network switch - not to a powerline adapter or Wi-Fi bridge unless you have confirmed those work reliably. Try the simplest possible connection for diagnosis: NAS directly to a port on your home router, computer also on the same router or switch. Rule out any intermediate devices first.
Step 2: Use the Vendor Discovery Tool, Not Windows
Windows file browsing (Network in File Explorer) uses WS-Discovery, a protocol that can be blocked by Windows Firewall or network configuration. The NAS vendor tools use a different broadcast discovery mechanism that is far more reliable. Always try the vendor tool first before concluding the NAS is unreachable.
For Synology: Download and run Synology Assistant from Synology's download centre. It broadcasts on the local network and lists any detected Synology NAS devices with their IP address, model, and status. If the NAS appears here, local discovery is working, but SMB or management access can still fail because of NAS-side service or firewall settings as well as Windows-side settings.
For QNAP: Download and run Qfinder Pro from QNAP's website. It works the same way - local broadcast discovery that finds QNAP devices on the network regardless of Windows network discovery settings.
Step 3: Check the IP Address and Subnet
For automatic broadcast discovery, the computer and NAS normally need to be on the same subnet; direct IP access can work across routed subnets when routing and firewall rules permit it. Your home network is typically 192.168.1.x or 192.168.0.x. If the NAS has a static IP address set outside the range your router uses - for example, 192.168.2.1 when your router uses 192.168.1.x - they cannot communicate directly.
To find your computer's IP address on Windows: open Command Prompt (Win+R, type cmd) and run ipconfig. Look for the IPv4 Address under your Ethernet or Wi-Fi adapter. Note the first three octets (e.g. 192.168.1). Compare both devices’ IPv4 addresses and subnet masks; matching the first three octets is sufficient only when both use a 255.255.255.0 (/24) mask.
If the NAS was previously on a different router and had a static IP configured, it may be unreachable because its static IP does not fit your current network. For a direct connection, follow the vendor’s link-local procedure rather than choosing an arbitrary 192.168.1.x address. QNAP specifies 169.254.100.99/255.255.0.0 for the computer; Synology says a directly connected NAS may self-assign 169.254.x.x and can be found with Synology Assistant. Once connected, change the NAS IP to DHCP to let your router assign it automatically.
Step 4: Check for an IP Address Conflict
An IP address conflict happens when two devices on the same network are assigned the same IP address. The most common trigger: the NAS has a static IP (e.g. 192.168.1.100) and the router's DHCP server also assigns that same address to another device. When two devices share an IP, both behave erratically - packets intended for one arrive at the other.
Log in to your router's admin interface (typically 192.168.1.1 or 192.168.0.1 in a browser) and look at the DHCP client table. This shows every device with an IP address assigned by the router. If you see two entries with the same IP, or if the NAS's IP does not appear in the list when it should, you have a conflict. Either switch the NAS to DHCP, or set the NAS static IP outside the router's DHCP range (Check the router’s actual subnet and DHCP pool, then use an otherwise unused address outside that pool or configure a DHCP reservation.).
Step 5: Windows Network Discovery and Firewall
If Synology Assistant or Qfinder Pro can find the NAS but Windows File Explorer's Network section cannot, the problem is Windows-side. Windows Network Discovery and file sharing must be enabled for the NAS to appear under Network in File Explorer.
On Windows 10 and 11: Go to Control Panel, then Network and Sharing Center, then Change advanced sharing settings. Ensure Turn on network discovery and Turn on file and printer sharing are both selected under Private networks. Also confirm that the network your NAS is connected to is classified as Private, not Public - Windows blocks many discovery protocols on Public networks.
To check the network profile: go to Settings, then Network and Internet, then your connection type (Ethernet or Wi-Fi). Under the connection properties, confirm it is set to Private. If it shows Public, change it to Private. Windows Firewall allows Network Discovery on Private networks and blocks it on Public.
Step 6: Access by IP Address Directly
Even if the NAS does not appear by name in Windows Network, you can usually reach it directly by IP address. Once you have identified the NAS's IP address using Synology Assistant or Qfinder Pro, type it directly into File Explorer's address bar as a UNC path: \\192.168.1.X where X is the NAS's address. If the NAS responds, you will see the shared folders and can log in with your NAS account credentials.
Similarly, the NAS web management interface is accessible by typing the IP directly into a browser: http://192.168.1.X:5000 for Synology, or http://192.168.1.X:8080 for QNAP (default ports - may differ if you changed them during setup). If the web interface works, IP connectivity to the management service is confirmed; SMB discovery and shared-folder access can still fail for separate NAS-side, Windows-side, protocol, firewall, or authentication reasons.
Step 7: Check SMB Protocol Version
SMB (the network file-sharing protocol Windows uses) must be running on the NAS and must be a version Windows supports. SMB1 is disabled by default in recent Windows versions (Windows 10 2004 and later). If the NAS is configured for SMB1 only, Windows will not be able to connect.
On Synology: Log in to DSM via its IP address in a browser (you can still reach the management interface even if Windows cannot browse it). Go to Control Panel, then File Services, then SMB. Confirm SMB is enabled, set the maximum SMB protocol to SMB3, and set the minimum SMB protocol to SMB2. If SMB1 is listed as the only enabled protocol, add SMB2 and SMB3 and disable SMB1.
On QNAP: Go to Control Panel, then Network and File Services, then Win/Mac/NFS/WebDAV. Confirm SMB/CIFS is enabled and the protocol version supports SMB2/SMB3.
When the Problem Is the Router or Switch, Not the NAS
Some routers block local network discovery between connected devices, particularly those with AP isolation or client isolation enabled. This feature is common on guest Wi-Fi networks and some consumer routers as a security measure - it prevents devices on the same network from communicating with each other. Depending on the router or access point, AP or client isolation may block communication between wireless clients only, or between wireless and wired clients as well; check the device’s documentation and the affected SSID.
Log in to your router's admin interface and look for AP isolation, wireless isolation, or client isolation settings. It should be disabled on your home or main network. Guest networks with isolation are acceptable and sometimes desirable - but the NAS should be on the main network, not the guest network.
Related reading: our NAS buyer's guide.
Related reading: our NAS explainer.
See also: our complete Synology NAS Australia guide.
See also: our complete QNAP NAS Australia guide.
Synology Assistant found my NAS but the status shows 'Not installed'. What does that mean?
Not installed means the NAS has been factory reset or a DSM installation has not been completed. Click the Install button in Synology Assistant to launch the DSM installation wizard in your browser. This is normal for a new NAS or one that has been reset. DSM can be installed automatically with internet access or manually by uploading a previously downloaded .pat file; completion time varies.
My NAS was working yesterday and is not visible today. What changed?
Possible causes of sudden loss of visibility include a changed DHCP address, a cable or link problem, and changed router or discovery settings. Check the router's DHCP client table for the NAS's current IP, then access it directly by IP. If you want stable NAS discovery, assign the NAS a static IP or configure a DHCP reservation so the router always gives it the same address.
How do I set a DHCP reservation so my NAS always gets the same IP?
Most home routers allow you to reserve a specific IP address for a device based on its MAC address. Log in to your router admin interface and look for DHCP reservations, address reservations, or static DHCP. Find your NAS in the DHCP client table (it will list the device name and MAC address), and create a reservation linking its MAC address to a specific IP. After saving, reboot the NAS so it requests the reserved IP. From then on, it will always receive the same IP address.
Can I access my NAS using its hostname instead of IP address?
Yes. Synology NAS devices register on the local network using mDNS (Bonjour) which allows you to reach them by hostname. By default, a Synology is accessible at NASNAME.local where NASNAME is the name you set during setup. On Windows, mDNS support requires Bonjour to be installed (it is included with iTunes or Apple's Bonjour for Windows). On Mac, it works without any additional software. QNAP uses a similar mechanism with NASNAME.local. This works on most home networks but may not work across network segments.
My NAS is visible in Synology Assistant but I cannot connect to its shared folders from Windows. What is wrong?
Discovery is working, but SMB access may still fail because of NAS-side SMB, firewall, account, or permission settings, or because of Windows-side connectivity or authentication settings. Check that Windows Network Discovery is enabled (Control Panel, Network and Sharing Center, Advanced sharing settings). Verify your NAS username and password in DSM - try connecting via \\NAS-IP in File Explorer and entering credentials manually. If Windows prompts for credentials but rejects them, check that the account on the NAS is not locked out and that the password has not changed.
Should I connect my NAS to the router or to a separate switch?
Either works correctly. A correctly configured switch on the same VLAN should not prevent discovery, but performance is limited by the switch and ports’ supported and negotiated speeds, configuration, congestion, and link health. The important factor is that all devices that need to communicate with the NAS - computers, routers, smart TVs - are on the same network segment (same subnet). Managed switches with VLAN configuration can inadvertently isolate the NAS from other devices if VLANs are misconfigured - on an unmanaged switch, this is not a risk.
NAS detected but file transfers dropping to zero? That is a different problem. The transfer speed troubleshooting guide covers cables, SMB settings, and drive health issues.