What the router was doing for you
A Windows computer set to use DHCP can assign itself an IP address when no DHCP server is available. A home router is normally the DHCP server. Remove it and nothing answers when either device asks for an address.
Microsoft's documentation says the reserved range for this fallback is 169.254.0.0 to 169.254.255.255. That range is Automatic Private IP Addressing (APIPA). Microsoft also notes that a PC using APIPA can only talk to machines on the same LAN that also use APIPA or have a matching 169.254.x.y address. It can't reach other subnets. An APIPA address is useful only for peer-to-peer communication, not for the Internet.
A QNAP community answer makes the practical point. On a direct connection, with no DHCP and no static addresses, the clients assign themselves addresses in 169.254.0.0/16. Those can change from time to time, so static addresses are the better choice.
There is a nuance. How-To Geek says both devices will fall back to APIPA. What a NAS does with no DHCP server depends on the model and firmware. It may self-assign a link-local address, keep a static address you set earlier, or behave differently. The robust fix is to remove the guesswork and configure both ends yourself.
Set it up: a step-by-step guide
You need an Ethernet port on each device and a patch cable. How-To Geek says modern adapters handle the old crossover wiring automatically, so a standard cable works. That is generally true of Gigabit and faster ports, but check your adapter specs if the link light never comes on.
1. Pick a separate subnet
Choose one that doesn't overlap your home LAN. If the router uses 192.168.1.x, use something like 10.0.0.x. The addresses below are examples, not requirements.
- PC: 10.0.0.1
- NAS: 10.0.0.2
- Subnet mask on both: 255.255.255.0
- Gateway and DNS: blank on this link
2. Set the static address on Windows 11
Microsoft's documented route is Settings > Network & internet > Ethernet, then the connected Ethernet network. Next to IP assignment, choose Edit, then switch Automatic (DHCP) to Manual. Turn on IPv4, enter the address and mask, and leave gateway and DNS empty.
The classic route also works. Run ncpa.cpl, right-click the Ethernet adapter connected to the NAS, and choose Properties. Then open the IPv4 properties and choose "Use the following IP address". Make sure you change the adapter that actually has the cable. A common mistake is saving the manual address on a different Ethernet adapter.
3. Set the NAS port
NAS menus differ by brand. Look for the network or interface settings for the port facing your PC. Switch it from DHCP to manual, then enter 10.0.0.2 and the same mask. TrueNAS, for example, has you set ipv4_dhcp to No and enter the static address with its subnet mask as an alias. Synology's DSM and other systems use different labels, so treat any single menu path as a guide, not a rule.
4. Test, then reach the share
Open Command Prompt and run ping 10.0.0.2. Replies show the two devices can exchange IP traffic. They don't prove that SMB is enabled, that a share exists, or that your account has permission.
Then try either of these:
- Type the NAS address into a browser to reach its management page.
- Map a drive in File Explorer using
\\10.0.0.2\ShareNameand your NAS credentials.
If it doesn't work
- Check the link lights on both ports and try a different cable.
- Run
ipconfigand see whether the PC shows a 169.254.x.x address. If so, the manual settings didn't stick or went to the wrong adapter. - Confirm the mask matches on both ends. Microsoft's subnetting guide says computers on the same physical network need addresses on the same IP subnet, or they can't communicate. Treat that as the rule for this link.
- Consider whether a firewall rule on the PC or a NAS setting is blocking ping or SMB.
The gateway warning, put precisely
How-To Geek says filling in a gateway "can break your internet connection." That is a safe rule, but not a guarantee of breakage. Microsoft's subnetting article explains that traffic for a remote network goes to the configured default gateway. A direct link has no router, so no gateway belongs on it. Microsoft's older KB on multiple default gateways warns that multiple default gateways can cause lost connectivity to remote networks. That article describes Windows NT-era behavior and is dated. The sensible takeaway is to keep the gateway blank on the private link so it can't compete with your real route to the internet.
What you give up
- Internet access for the NAS. On that cable it can't fetch firmware, sync to cloud services or reach an NTP server.
- Access from other devices. Phones, TVs and other PCs on your LAN won't see the NAS through that cable.
- Simplicity. The PC needs a second connection, such as Wi-Fi or another Ethernet port on the router, to stay online.
Is it actually faster?
Not necessarily, and no measured comparison backs the claim. Speed depends on the link rate at both ends, the storage in the PC and NAS, and other bottlenecks. A router with Gigabit ports adds little latency to a LAN transfer. A direct cable helps most when it lets you use a faster link, such as 2.5G or 10G, than your switch or router offers. That is general networking knowledge, not a result from this story.
A common compromise is to give the NAS a DHCP reservation on the router. If you use a second NAS port or a spare PC adapter for the direct link, use a different subnet for it than your home network.
Undoing it
Before returning the PC's adapter to a normal network, switch IP assignment back to Automatic (DHCP). Note the original IP settings first so you can reinstate them later. Microsoft recommends DHCP where available, because you won't have to change settings when you move to another location.
Bottom line
A direct PC-to-NAS cable works if you set matching static IPv4 addresses, use a private subnet and leave the gateway blank. It gives up network-wide access and internet services for the NAS. For most homes the router-connected LAN is simpler. The direct link is mainly worth it for a dedicated high-speed or isolated connection.