When a NAS is not detected on the network, the problem is almost never the NAS hardware - it is almost always a discovery protocol issue, an IP address conflict, a firewall blocking network discovery, or the NAS being on a different network segment than the computer looking for it. 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 its network light is solid (not blinking or off). 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 broadcast discovery that bypasses most network configuration issues. 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 network LED is off, the cable is not connected or is faulty. 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 your NAS appears here, your NAS is reachable - the problem is on the Windows browsing or firewall side, not the NAS side.
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 a computer to find a NAS, both must be on the same IP subnet. 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). The NAS must have an IP address with the same first three octets to be on the same subnet.
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. In this case, connect the NAS with a direct Ethernet cable to the computer (not through a router), set the computer's IP manually to 192.168.1.100/255.255.255.0, and access the NAS via Synology Assistant or Qfinder Pro which work on direct connections. 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 (most routers assign in the range 192.168.1.100-200, so a static IP of 192.168.1.50 is typically safe).
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 this works, the NAS is reachable on the network - the problem is only in how Windows discovers it by name, not in connectivity itself.
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 and that the minimum protocol is set to SMB2 or SMB3. 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. If AP isolation is enabled on your network, the NAS and your computer cannot see each other even though both are connected to the same router.
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.
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. The installation process takes about 10 minutes and requires the NAS to download the latest DSM version from Synology's servers, so ensure the NAS has internet access during setup.
My NAS was working yesterday and is not visible today. What changed?
The most common causes of sudden loss of visibility are: the router's DHCP server assigned a different IP address to the NAS (happens after a router reboot if the NAS uses DHCP), the network cable became partially disconnected, or a router firmware update changed network 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?
This is a Windows connectivity issue, not a discovery issue. The NAS is reachable but Windows cannot authenticate or connect to its SMB shares. 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 switch between the NAS and router adds a hop but does not degrade network discovery or performance on a Gigabit or 2.5G network. 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.
Fix Transfer Speed Drops