Sharing files between computers in the same house shouldn't require carrying a USB drive between them. It doesn't — both major operating systems can share folders over your home network, and they can read each other's shares.
Here's the minimum networking knowledge to make that work, and the settings that matter.
The concepts you actually need
Your router is the box that connects your home to the internet and connects your devices to each other. Everything on your network talks through it.
Local network versus internet. Devices in your house can talk to each other directly, without traffic leaving the building. File sharing between two computers at home doesn't touch the internet at all, which is why it's fast and why your internet speed is irrelevant to it.
IP addresses. Every device gets a number on your network, usually something like 192.168.1.x. These are assigned automatically. You occasionally need to know a device's address to connect to it directly.
Wired versus wireless. A cable is faster, more consistent, and lower latency than wifi. For moving large files, the difference is substantial — often several times faster.
That's genuinely all the theory required.
Wired versus wireless, in practice
Use a cable for: anything stationary — a desktop, a NAS, a media player, a games console. And for any large file transfer, even temporarily.
Wifi is fine for: phones, tablets, laptops in normal use, and streaming.
The bottleneck is usually wifi, not your equipment. People conclude their NAS is slow when actually their laptop is on a congested wireless band two floors away.
If you can't run a cable: powerline adapters send network traffic over your electrical wiring, and results vary considerably depending on the house. Mesh wifi systems improve coverage substantially and are still wireless. Both are better than a weak wifi signal and neither matches a cable.
Improving wifi, briefly
Router placement matters more than anything else. Central, elevated, out in the open. Not in a cupboard, not behind the TV, not on the floor in a corner. Signal is blocked by walls, water, and metal — a router next to a boiler or a mirror is compromised.
Use the right band. Modern routers broadcast on multiple frequency bands. The lower band travels further through walls and is slower; the higher bands are faster over shorter distances. If your devices let you choose, put stationary devices on the faster band and roaming ones wherever the signal is best.
Change the channel if you're in a dense area with many neighbouring networks. Most routers can scan and pick a clearer one.
A mesh system genuinely helps in larger or awkwardly-shaped homes, more than a single powerful router does.
Setting up folder sharing
On a Mac
- System Settings → General → Sharing
- Turn on File Sharing
- Add the folders you want to share under Shared Folders
- Set who can access each — specific users, with read-only or read-write
- Note the address shown, usually something like
smb://Laurie-MacBook.local
On Windows
- Right-click the folder → Properties → Sharing → Advanced Sharing
- Tick Share this folder, set permissions
- Make sure network discovery and file sharing are enabled in network settings
- Set your network profile to Private, not Public — sharing is blocked on public networks by design
Connecting from the other machine
From a Mac: Finder → Go → Connect to Server → smb://computername.local or the IP address.
From Windows: File Explorer → Network, or type \\computername in the address bar.
Both platforms use the same underlying protocol, so Mac-to-Windows sharing works fine once both ends are configured.
If the computer name doesn't work, use the IP address. Name resolution on home networks is unreliable; IP addresses always work.
Finding a device's IP address
Mac: System Settings → Network → your connection → Details. Windows: Settings → Network → Properties, or run ipconfig in a command prompt. Router admin page: shows every connected device and its address, which is often the easiest route.
Set a static or reserved address for anything you connect to regularly — a NAS, a shared desktop. Otherwise the address can change when the device reconnects, and your saved shortcuts break. Most routers can reserve an address for a specific device.
Common problems
"I can see the computer but can't connect." Usually credentials. You need an account on the sharing machine, not just network access. Create a user for the purpose if needed.
"The computer doesn't appear at all." Check the network profile is Private on Windows, check both machines are on the same network (not one on a guest network), check firewalls, and try the IP address directly.
"It's very slow." Almost always wifi. Try one end wired and see if it changes. Also check whether an antivirus product is scanning everything passing over the network.
"It disconnects randomly." Sleep settings. Machines that sleep drop their shares. Set the sharing machine not to sleep, or accept waking it first.
"Permission denied on some files." Permissions on the shared folder don't match the connecting user. Adjust on the sharing side.
Guest networks and separation
Most routers can broadcast a separate guest network. Use it.
Guests go on the guest network. They get internet and cannot reach your computers, your NAS, or your shared folders.
Smart home devices belong there too, if your router allows it. Cameras, speakers, doorbells, and various cheap connected gadgets are frequently poorly secured and rarely updated. Keeping them off the network where your files live is a meaningful reduction in risk.
This is one of the highest-value router settings available and one of the least used.
Router security, which people neglect
The router is the front door, and most people have never logged into it since installation.
Change the admin password. Not the wifi password — the password for the router's own settings page. Default admin credentials are published for every model.
Update the firmware. Router vulnerabilities are actively exploited. Check for updates, and enable automatic updates if available. A router more than five or six years old may no longer receive updates at all, which is a reason to replace it.
Use WPA3, or WPA2 if that's the best available. Turn off older, broken options if they're still enabled.
Use a strong wifi password. A passphrase of several random words.
Turn off WPS, the push-button pairing feature. It has known weaknesses.
Turn off remote administration unless you specifically need it. Router admin pages reachable from the internet are a well-known target.
Turn off UPnP if you can live without it. It lets devices open ports automatically, which is convenient and occasionally exploited. Some games and applications need it.
Don't forward ports to devices in your house unless you understand the consequences. Exposing a NAS or a computer directly to the internet is how most home network compromises happen.
Accessing files from outside the house
Sometimes you want your home files while away. Options, in order of safety:
Cloud storage. The simplest answer for most people. The files sync, and you reach them from anywhere without exposing anything at home.
A VPN into your home network. Many routers and NAS devices can run one. You connect to your home network securely and everything works as if you were there. This is the right approach for reaching home devices remotely.
The manufacturer's remote access service, for a NAS. Convenient, and you're trusting the vendor's implementation. Enable two-factor authentication if you use it.
Port forwarding to expose a device directly. Don't. This is how internet-exposed NAS devices get compromised, and it happens at scale.
Sharing a printer, while you're here
Same mechanism. Both platforms can share a connected printer over the network, and most modern printers connect to wifi directly and are visible to everything without a host computer.
If a printer has an internal drive — many business machines do — remember it stores what's printed and scanned, and needs wiping before disposal.
The setup worth having
- Router admin password changed from default
- Firmware updated, automatic updates on
- WPA3 or WPA2, strong passphrase
- WPS off, remote administration off
- Guest network enabled, used for guests and smart home devices
- Router placed centrally and in the open
- Stationary devices wired where practical
- File sharing configured on the machines that need it
- Reserved IP addresses for devices you connect to regularly
- VPN or cloud storage for remote access — not port forwarding
The router items take twenty minutes and are the highest-value security work most households can do. The sharing setup takes ten and saves carrying drives around the house indefinitely.
Next in this series: How to Create a Home Server on a Budget