DHCP Reservation Not Working? Causes and Fixes

What a DHCP reservation does

A DHCP reservation is a rule on your router that says a specific device always receives the same IP address. The router identifies the device by its MAC address and skips the normal dynamic assignment process for that entry. If the reservation is working, the device's address never changes, which is useful for port forwarding, printer sharing, and home server access. For background, see DHCP explained and MAC addresses explained.

When a reservation fails, the router is still handing out addresses, but the expected device is not getting the one you reserved. The root cause is usually one of four things: a stale lease, an address conflict, a wrong MAC address, or a firmware or configuration issue.

Fix stale leases first

A device that connected before you made the reservation may keep using the address it already received until the lease expires. The reservation only controls future assignments, not an active lease. That is why your first step is to break the old lease.

Reboot the router and then reboot the device. If the device is a phone or laptop, turn Wi-Fi off and on, or forget and rejoin the network. On a desktop, release and renew the IP address if your operating system provides that option. If the device is a printer or smart-home gadget, power-cycle it after the router is back online.

If the device keeps returning with the wrong address, shorten the DHCP lease time temporarily so stale addresses clear faster, then restore your normal lease time after the device picks up the reserved address. See DHCP lease time explained and how to see connected devices on a router.

Confirm the MAC address you reserved

A reservation binds an IP address to one MAC address. Many devices have more than one: a Wi-Fi adapter MAC, an Ethernet MAC, and sometimes a Bluetooth MAC. If you copied the address from a previous connection or from a device sticker, you may have reserved the wrong one.

Open the router's connected-device list and compare the device currently on your network with the MAC address in the reservation. The addresses must match exactly, including colons and letter case. Some routers expect the address without separators, so follow the format shown in the reservation page. For the difference between IP and MAC identity, see IP address vs MAC address.

Check for IP conflicts and DHCP pool overlap

The most common reservation failure is overlap. Most routers assign dynamic addresses from a pool, and reservations are often made in the same area. If the reserved address is inside the dynamic pool, the router may hand that address to another device before the reserved device asks for it. That creates an IP conflict or simply gives the reserved device a different address.

Open the router's LAN settings and look at the start and end addresses of the DHCP pool. Pick a reserved address outside that range, or shrink the pool so it no longer includes the addresses you want to reserve. Avoid giving the same static address to a device manually while a reservation for that address still exists, because the two settings can fight each other.

If you use a second router, access point, or mesh node that is still in router mode, its DHCP server can hand out addresses on the same network. Put that device in bridge or access point mode so only one device manages DHCP. See bridge mode explained and double NAT detected.

Update firmware and review router settings

Router firmware controls the DHCP server. A reservation bug can be fixed in a firmware update, and a failed update can leave settings in an odd state. Check the router admin page for updates and install them, then reboot the router and confirm the reservation is still listed. See how to update router firmware and how to back up and restore router settings.

Some routers apply DHCP changes only after a reboot. If the reservation was added while the router was under load or the settings page timed out, the rule may not have been saved. Review the reservation list, delete and recreate the entry, and back up your settings once it works.

After a firmware update or factory reset, reapply reservations carefully. A factory reset clears all custom rules, including reservations. If a reset happened recently, that alone explains why the old reservation stopped working. See how to factory reset a router.

When to use a static IP instead

If your router's reservation feature is buggy and you cannot update the firmware, you can set a static IP address on the device itself. Choose an address outside the router's DHCP pool, enter the subnet mask, default gateway, and DNS server addresses from the router's LAN page, and then test connectivity.

A static IP is a fallback, not a permanent replacement for DHCP. The router cannot manage or change a static address, and you may need to update it if you change networks. A working reservation is usually cleaner because all address rules stay in one place. Compare both approaches in DHCP reservation vs static IP and how to set up DHCP reservation on a router.

What to pick for your use

Questions

Why did my router stop honoring a reservation that used to work?

Most often a device kept a stale lease or the reserved address now falls inside the DHCP pool. Renew the lease, confirm the MAC address, and move the reserved address outside the pool.

Should I use a DHCP reservation or a static IP?

A reservation is easier to manage because all assignments stay in the router. A static IP on the device is a good fallback if the router's DHCP is buggy, but you must keep the device settings aligned with the network.

Does rebooting the router fix a DHCP reservation?

It can. Rebooting clears active leases and forces devices to request addresses again. If the reservation is correct, the device usually picks it up after the router returns.

Can two routers break DHCP reservations?

Yes. If a second router or an access point is still in router mode, it can run its own DHCP server and assign a different address. Use bridge or access point mode so only one DHCP server operates.

Do mesh systems support DHCP reservations?

Most do, but the setting may be in the companion app rather than a web page. Check the main node's LAN settings, and make sure satellites are not running their own DHCP servers.

Can firmware updates really fix reservation problems?

Yes. DHCP behavior is implemented in firmware, and vendors regularly release updates for address-assignment bugs. Keep firmware current and reapply reservations after a factory reset.