What a DHCP reservation is, and how to set one on your router

Short answer: a DHCP reservation is a setting on your router that ties one device’s MAC address to one IP address permanently. The device still gets its address through normal DHCP, but the router always hands it the same one instead of a different address from the pool. It’s the fix for a device that keeps losing a fixed address after a reboot.

Why an address moves in the first place

Your router runs a DHCP server, which is the piece that assigns local addresses to devices as they connect. As covered in static IP vs dynamic IP, those addresses come from a pool the router manages, and a device usually gets the same one back each time it renews its lease. But “usually” isn’t “always.” A router reboot, a factory reset, or a device rejoining after a long time offline can all cause DHCP to hand out addresses in a different order than before.

For a laptop or a phone, this is invisible. For anything another device points at directly, it’s a problem.

What actually breaks

A few setups depend on a device staying at one address:

• A port forwarding rule aimed at 192.168.1.50 stops working the moment the device that used to sit at .50 gets handed a different address.
• A NAS or media server that other computers connect to by typed-in IP instead of a name.
• A printer added to several computers by its address, which fails quietly the day that address shifts.
• A security camera or smart-home hub with its own app hardcoded to one address.

A DHCP reservation fixes all of these the same way: it makes the address stop moving.

Reservation vs a manual static IP

You could also set a static IP by hand on the device itself, switching its network settings from automatic to manual. The difference is who’s in charge. A manual static IP means the device stops asking the router for anything, so if the router doesn’t know that address is taken, it can hand the same one to something else and cause a conflict. A reservation keeps DHCP running normally and just tells the router which address belongs to which device, so the router itself avoids handing that address out twice. For a home network, the reservation is almost always the simpler and safer of the two.

How to set one up

The exact screen varies by brand, but the steps are close to identical everywhere:

1. Open your router’s admin page. If you don’t know the address, finding your router’s IP covers it per operating system.
2. Look for “DHCP,” “LAN Setup,” or “Address Reservation” in the menu. Some brands label it “Static DHCP” instead.
3. Find the device in the connected-clients list. It’s usually shown by its device name and its MAC address — the MAC is how the router tells devices apart even when their IP changes.
4. Assign it a fixed address. You can usually keep the one it already has, which avoids re-pointing anything that already references it.
5. Save, and give the device a moment to renew its lease. A quick disconnect and reconnect (or a reboot) forces it to pick up the reserved address right away.

Picking which address to reserve

If you’re reserving a new address rather than keeping the device’s current one, pick something outside the range your router hands out automatically. Most routers show that range on the same DHCP settings page, often something like 192.168.1.100 through 192.168.1.200. An address just below or above that range, like 192.168.1.50, stays out of the router’s way and won’t get handed to another device later.

When a reservation isn’t enough

A reservation only fixes the device’s address on your own network. If you’re trying to reach that device from outside your home, you still need a port forwarding rule pointed at it, or a service designed for remote access. The reservation just makes sure that rule keeps working after the next reboot instead of quietly breaking.