Local IP

What Is a Local IP

The local IP is the internal address that the device receives within the local network (home, office, cafe with Wi-Fi). Such an IP address is not needed to access the Internet directly, but so that computers, phones, and routers can communicate with each other within this network.

To make it easier: Public IP is your “home address” on the Internet, visible to the whole world. And the Local IP is the “apartment number” inside your building. You can’t see it from the outside, but it’s critically important for life inside.

Why do we need such addresses?

• So that the laptop and printer can find each other.
• So that the smartphone can transfer files to the TV via Wi-Fi.
• So that corporate networks with hundreds of PCs do not occupy thousands of unique public IP addresses.

Thus, Local IP is a working environment for communication within a network that is hidden from the entire Internet. In order to perfectly understand everything about IP addresses please check our article.

How Local IP Works

The local IP is assigned to the device either automatically or manually. In most cases, this is controlled by a DHCP server built into the router. It distributes addresses to all connected devices: a laptop, a phone, a set-top box, even a smart kettle.

There are several reserved ranges for local area networks (RFC 1918):

• 192.168.x.x is the most popular (for example, 192.168.0.101 for a laptop).
• 10.x.x.x is more common in corporate networks.
• 172.16.x.x – 172.31.x.x — intermediate range, used less frequently.

Devices with such addresses can see and communicate with each other, for example, using SMB or AirDrop protocols. But they can’t access the Internet directly with this address — they need NAT (Network Address Translation), which the router does automatically.

Historical Background: From Public to Local IP

At the beginning of the Internet, everything was simple: each device could be assigned its own Public IP. But the Internet was growing, and IPv4 addresses were limited (only about 4.3 billion). In the 1990s, it became obvious: “there are not enough addresses for everyone.”

To solve the problem, the RFC 1918 standard was adopted, which reserved entire ranges for Local IP. These addresses are not routed on the Internet, but only work inside private networks.

At the same time, NAT technology appeared, which allows dozens of devices inside the house to sit behind one common Public IP. The router, as a “translator”, replaces the Local IP with the Public IP and vice versa.

This step was a turning point: Local IP became not just a technical detail, but the foundation of a scalable Internet. Without it, the networks of providers, offices and homes simply could not exist.

Key Uses of Local IP

Local IP is the basis of almost any network, from an apartment to a data center.

• Home networks. Your router receives one Public IP from the provider, and then distributes a Local IP to each device. The laptop gets, say, 192.168.0.15, the phone gets 192.168.0.16, and the console gets 192.168.0.17. This way they can see each other and work in parallel through one common Internet outlet.
• Corporate networks and VLANs. In offices, Local IP allows you to divide the network into segments. Accounting is in one subnet, IT is in another, and marketing is in the third. This is called VLAN, and it increases security and manageability.
• IoT and local services. Smart light bulbs, cameras, kettles — all this works on Local IP. They rarely have direct access to the Internet, but they communicate inside a local network while your smartphone controls them through a router.
• Safety. Local IP is also protection. If the device has only an internal address, it cannot be “reached” directly from the Internet. It’s hidden behind the NAT and the router.

Common Issues with Local IP

Of course, Local IP has enough problems.

• IP conflicts within the network. If two devices accidentally receive the same address (for example, 192.168.1.100), they will interfere with each other and the Internet will not work.
• DHCP errors. Sometimes the router stops distributing addresses correctly. In this case, the device either does not receive an IP at all, or you see a strange “emergency” address like 169.254.x.x.
• NAT problems. When too many devices are using the same Public IP, errors may occur in games, apps, or VPNs. For example, the service “thinks” that all 50 employees in the office are the same user.
• Incorrect IP address. It happens that instead of the normal Local IP, the device receives the “wrong” address — just 169.254.x.x (fallback), or a random public IP that does not work on the local network. All this indicates failures in the DHCP or settings.

Troubleshooting the local IP address (troubleshooting)

The result: in 80% of cases, users with local IP addresses have a basic configuration: fast DHCP, address connectors, DNS, and a local router. Below is a short “ambulance algorithm” + in—depth steps.

Step 0. Quick triage (1-2 minutes)

1. Connect the network: turn on Wi-Fi, install Ethernet.
2. Restart the router (turn off the power for 20-30 seconds).
3. Check the IP: either it is 169.254.x.x, or APIPA → connect to the DHCP/channel.
4. Check another website at http://1.1.1.1 or http://8.8.8.8

• Either the IP pages open, or there is no domain, or DNS is a problem.
• Nothing opens — the problem is below (DHCP, root, access).

Step 1. See what the network and OS have given out

• Windows: ipconfig /all. Specify the IPv4 address, default gateway, and DNS servers. The gateway must be from your network (example, 192.168.1.1).
• macOS: System Settings → Network → (interface) → Details → TCP/IP → Extend the DHCP lease if necessary.
• Linux: ip address, ip route, nmcli dev mapping
• iOS/Android: There is an IP/DNS/login on the Wi-Fi network. On iOS, you can “Extend the lease”, on Android — “Forget about the network”.

Alarms:

• There is no access (default gateway) or it is not from your network → DHCP/router.
• DNS from the “left” section or just → check the DHCP/DNS settings in the router.
• 169.254.x.x → DHCP is unavailable, see section 3.

Step 2. Provide communication with internal networks (L2/L3)

1. Ping code: ping 192.168.1.1 (install you). No response → cable/router/segmentation.
2. ARP and IP links:
   • Windows: arp -a • macOS/Linux: arp -a If you have two friends, then this is your IP, but not a different MAC address. Change: transfer IP (DHCP), split the reservation (DHCP Reservation), enable simple management in a DHCP/other statistical address.
3. Default route:
   • Windows: Print routing
   • Linux/macOS: IP routing
   • You must set the default view string to 192.168.1.1. If you are not using a DHCP server.

Step 3. If you see 169.254.x.x (APIPA)

• Windows:
  • ipconfig /release
  • ipconfig /update
  • services.msc → DHCP client (not running yet)
• macOS: We extend the DHCP lease; if not necessary, we remove ourselves from the network and connect to it.
• Linux:
  • sudo dhclient -r && sudo dhclient
  • sudo systemctl restarts NetworkManager
  • journalctl -u NetworkManager | grep -i dhcp
• iOS: Settings → General → Transfer or Reset settings → Reset network settings (for example: “Extend lease”).
• Android: Forget about the network → connect to the network; select the necessary settings → System → Reset settings for Wi-Fi, mobile devices and Bluetooth.

If version 169.254 is not installed yet, then the new version of DHCP does not work on the router (or the DHCP tracker is blocked).

Step 4. Interface: DHCP, Files, NAT, DNS

1. Is DHCP enabled? Make sure that there is no server for the DHCP address and user addresses (for example, 192.168.1.100-192.168.1.200).
2. Request slides: if the main server is 192.168.1.0/24, the second one (not yet available), then it is developing a mess DHCP server. Disable DHCP for additional users/Wi-Fi users.
3. DNS on the router: install the initial versions (1.1.1.1 / 8.8.8.8 / 9.9.9.9 ), or use a DNS server.
4. NAT/Firewall: Make sure that the NAT is connected to the WAN interface, local traffic (including DHCP/UDP 67-68) is not blocked.
5. Enabling the router firmware: Some DHCP banks provide a partial “available” service.

Step 5. Use “masking” programs (VPN/Proxy/Captive Portal)

• VPN/access: permanently disable. Some operators intercept/disable DHCP or change DNS.
• Captive portal (hotels/kache): the user had to hide the information from the users. If it is not disclosed, enter the password. http://neverssl.com — the part “unlocks” the portal.

Step 6. DNS vs Internet

• If the sites are opened by IP (1.1.1.1), then they are not:
  • Install the advanced DNS on the wedge (1.1.1.1 and 8.8.8.8) and connect to the DHCP server.
  • Check out nslookup ya.ru / dig ya.ru (Linux/macOS) — what response will you get?

Step 7. Special cases (offices, advanced)

• VLAN/802.1X/MAC integration: perhaps this is why there is an SSID to which a user is connected who is part of “your” VLAN with DHCP support.
• Access opens to: either a desktop with a VPN interface 192.168.1.0/24, or to you, just a range – there will be a contact of tokens. Replace the house with another one (for example, the number 192.168.50.0/24) or build a separate tunnel.
• IPv6/IPv4 protocol conflict: You may temporarily disable IPv6 if you are debugging specifically for IPv4 access, so as not to get confused about prefixes/routes.

Step 8. When to Escalate

• Please connect to all network devices → specify the user password/DHCP or administrator password.
• Find partial links to IP → install statistics in DHCP by MAC addresses.
• Standard Wi-Fi → check channel, go, interference, location to the point, sirina channel and more.

Mini checklist (total)

1. Renew the IP/DHCP lease.
2. Use DNS.
3. Pinglisa, arp-a, route printing / IP route.
4. Connect a VPN/proxy; create your own portal.
5. Check/enable DHCP on the router, pul, DNS, NAT; complete the download.
6. Replace the phone with another one if it is connected to a VPN.
7. On mobile — Airplane mode, Forget about the network, Reset network settings.