What Is DHCP? How Your Router Hands Out IPs
DHCP lets your router give every device an IP address automatically. Here is how it works and how to use reservations.
DHCP (Dynamic Host Configuration Protocol) is the service on your router that gives every device an IP address, subnet mask, gateway and DNS server automatically when it joins the network.
DHCP is the service on your router that gives every device an IP address, subnet mask, gateway and DNS server automatically when it joins the network.
Without it you would type network settings into every phone and laptop by hand. Here is how it works and the settings worth knowing.
How DHCP works
- Discover: your device joins WiFi and asks for an address.
- Offer: the router offers a free address from its range.
- Request: the device accepts it.
- Acknowledge: the router confirms and records the lease.
The device keeps the address for the lease time, often 24 hours, then renews it. The four-step handshake is the part I explain first when DHCP feels mysterious.
DHCP settings in your router
| Setting | Typical value | What it does |
|---|---|---|
| DHCP server | On | Hands out addresses |
| Start address | 192.168.1.100 | First address in the pool |
| End address | 192.168.1.199 | Last address in the pool |
| Lease time | 1 day | How long a device keeps an address |
| DNS | Router or public DNS | Sent to every device |
| Reservations | MAC to IP list | Fixed addresses for chosen devices |
The lease-time row is the one I point at first when the pool looks small.
How to reserve an IP address
- Log in to your router admin page. Find the address with our Router IP Finder, or try 192.168.1.1 or 192.168.0.1.
- Open LAN, DHCP or Address Reservation.
- Choose the device from the list, or enter its MAC address.
- Pick an address and save. The device gets it every time it connects.
Reservations are ideal for printers, NAS drives, cameras, game consoles and port forwarding targets. The printer reservation is the one I set first on any home network.
Common DHCP problems
- 169.254.x.x address: the device got no reply from DHCP. Restart the router.
- Two DHCP servers: a second router hands out its own addresses. Turn DHCP off on one of them.
- Pool full: many devices and a small range. Widen the range or shorten the lease.
- “DHCP is not enabled for WiFi” on Windows: set IP to Automatic in adapter settings.
The 169.254 address is the clue I look for first when DHCP goes quiet.
DHCP lease time, explained
When your router gives a device an address, it’s a loan, not a gift. The lease time says how long the device can keep it before asking again. Routers often use 24 hours or a few days.
Devices renew their lease quietly before it runs out, so you rarely notice. Short leases suit cafés and offices with lots of visitors. Long leases suit homes where the same devices stay connected. For me, the 24-hour lease is the default I leave alone in most homes.
Two DHCP servers on one network
A classic home mistake is having two routers both handing out addresses, for example an ISP router and your own router connected LAN to LAN. Devices can end up with addresses from either one, and some lose internet randomly.
Only one device should run DHCP. If you add a second router, set it to access point mode or turn its DHCP server off. The access-point switch is the fix I reach for first when two routers fight.
What a DHCP server hands out
DHCP gives a device more than just an IP. A typical lease includes:
- IP address: like 192.168.1.20.
- Subnet mask: usually 255.255.255.0.
- Default gateway: the router’s address.
- DNS servers: for name lookups.
- Lease time: how long the address is valid.
If any piece is wrong, the device may connect to WiFi but fail to reach the internet. The missing-gateway case is the one I check first when WiFi connects but nothing loads.
Change your DHCP range
- Log in to your router and open LAN or DHCP settings.
- Find the start and end addresses, for example 192.168.1.100 to 192.168.1.199.
- Widen the range if you have lots of devices.
- Keep space outside the range for static devices like printers.
- Save and restart devices that need new addresses.
The keep-space-outside tip is the one I never skip when a range gets widened.
DHCP on mesh and access points
In a mesh system, only the main unit runs DHCP. Satellites pass addresses through from it. When you add a second router as an access point, turn its DHCP server off for the same reason. One DHCP server per network keeps addresses tidy and avoids devices losing internet at random.
The one-server rule is the line I repeat most in any two-router home.
