Router Not Assigning IP Addresses: DHCP Diagnosis and Fix

Router DHCP not assigning IP addresses — devices connecting to the Wi-Fi but showing “No Internet” or getting stuck at 169.254.x.x addresses, or DHCP simply running out of IPs to hand out — is a problem that sounds complicated but is usually solved in minutes once you figure out whether it’s one device or all devices. That distinction matters a lot. For a broader walkthrough, our Complete Guide to Fixing Windows, Browser, and Software Errors is a good next read.

Check immediately: are all devices affected, or just one? Open another device (phone, different laptop) on the same network and see if it gets a working IP (a normal 192.168.x.x address). If the phone works fine but the laptop doesn’t: the problem is that specific device’s DHCP request or saved network config, not the router’s DHCP server. If nothing can get an IP from the router: DHCP is broken at the router level.

Single device can’t get an IP

On Windows 11: open Command Prompt as Administrator → run ipconfig /release then ipconfig /renew. This drops the current IP lease and requests a new one from the router. If ipconfig shows a new 192.168.x.x address after this: fixed. If it shows 169.254.x.x or “Media disconnected”: the renewal request isn’t reaching the router, or the router refused the request.

Also try: Settings → Network → Wi-Fi → your network → “Forget” → reconnect. The forget removes the saved profile including any cached IP configuration. After reconnecting, Windows requests a fresh DHCP lease rather than trying to renew the old one.

The Winsock/IP stack reset helps when the Windows networking stack is in a bad state: open Admin Command Prompt and run:

netsh winsock reset
netsh int ip reset
ipconfig /flushdns

Restart after these three. This resets the TCP/IP stack to clean defaults, which resolves DHCP failures caused by corrupted networking configuration rather than the router itself.

All devices can’t get IPs — router DHCP exhausted

DHCP servers have a pool of IP addresses they can assign. A typical home router might have a pool of 50 addresses (192.168.1.2 through 192.168.1.51). When all 50 are in use — or more accurately, when 50 leases are active — no new device can join.

Log into the router admin (usually 192.168.1.1 or 192.168.0.1) → DHCP settings → look for “DHCP client list” or “Connected devices.” Count how many leases are active. If it’s near your pool limit: either expand the pool range (change the end address from .51 to .100), or reduce the lease time (e.g. from 24 hours to 2 hours) so expired leases free up faster.

Common cause of DHCP exhaustion: a device (smart TV, IoT device, old router acting as AP) is obtaining a new IP every time it reconnects rather than renewing its existing lease. Each reconnect grabs a new slot without releasing the old one, gradually consuming the entire pool. The DHCP client list in the router usually shows duplicate MACs or many entries for devices that shouldn’t be so numerous.

DHCP service stopped on the router

The DHCP server on the router can be disabled accidentally, or it may have crashed. Router admin → DHCP Settings → ensure “DHCP Server” is enabled. On some routers (particularly those running DD-WRT, OpenWRT, or similar firmware): the service needs to be explicitly enabled and configured rather than being on by default.

The quickest fix for a crashed router DHCP service is a full router power cycle: unplug the router from power → wait 30 seconds → plug back in → wait 2 minutes for it to fully boot → test connectivity. Power cycling restarts all router services including DHCP. If the problem returns: the router has a recurring service crash worth investigating further.

Static IP conflict causing DHCP confusion

If a device has a manually-assigned static IP (configured directly on the device) that falls within the DHCP pool range: DHCP may try to assign that same IP to another device, creating a conflict. Both devices then have the same IP, and neither can communicate reliably.

Fix: either remove the static IP from the device and let DHCP handle it, or configure a DHCP reservation for that device in the router (which gives it the same IP every time through DHCP rather than a hardcoded static). Better practice: if you need devices to have fixed IPs (printers, NAS drives, cameras), use DHCP reservations rather than static IPs set on the device — the router manages the assignments, preventing conflicts.

Our guide on Wi-Fi connectivity troubleshooting covers the connection failures that sometimes accompany DHCP issues, and our DNS server problems covers the related symptom of connected-but-no-internet that DHCP failure can cause. For router DHCP configuration including reservation setup, your router’s manual or manufacturer support page covers the specific menu paths for your model.

DHCP lease time — how it affects IP availability

DHCP leases have an expiry. A 24-hour lease means the router reserves that IP for 24 hours after last contact with the device. If a device leaves the network (goes to work, goes to bed, gets turned off), the router keeps the IP reserved for 24 more hours before releasing it for reassignment.

In environments with many devices cycling on and off (guest networks, student accommodation, offices): a 24-hour lease creates a pool exhaustion problem over time. Reducing lease time to 2-4 hours lets IPs cycle back into the pool faster. In stable home environments: 12-24 hours is fine and reduces DHCP request traffic on the network.

The lease renewal process: devices renew at 50% of the lease time (at 12 hours for a 24-hour lease). If the device can’t reach the router to renew: it continues using the IP until 87.5% of the lease time, then tries more aggressively. If renewal fails completely: the lease expires and the device loses the IP, falling back to 169.254.x.x (APIPA). This is why a laptop that sleeps overnight sometimes loses its IP — the lease expired while sleeping and DHCP renewal failed on wake-up.

Router DHCP logs

Most routers log DHCP events. Router admin → System Log or DHCP Log → look for “DHCP request denied,” “Pool exhausted,” or “Lease conflict” entries. These specific log entries point directly at the cause:

• “Pool exhausted”: too many active leases; expand pool or reduce lease time
• “Request denied” with a MAC address: MAC filtering is blocking that device
• “Duplicate IP detected”: static IP conflict; check which devices have manually assigned IPs
• “Lease renewal rejected”: device is trying to renew a lease that expired; reconnect to get a new one

MAC address filtering and DHCP

If MAC address filtering is enabled on the router: only approved MAC addresses can receive DHCP leases. New devices — including any device with a new network adapter or a Windows 11 device using “Random hardware addresses” (which presents a different MAC each time) — are refused by DHCP.

Check: router admin → Wireless → MAC Filter → is filtering enabled? If yes and a specific device can’t get an IP: add its MAC to the allowed list, or disable MAC filtering (it provides minimal security benefit while creating significant administrative overhead).

Windows 11’s random MAC addresses are enabled by default and particularly problematic with MAC filtering. Each time a Windows 11 device forgets and reconnects to a Wi-Fi network, it may present a different MAC address. The MAC filter needs the random MAC that Windows is currently using for that network, not the hardware MAC printed on the device. Settings → Network → Wi-Fi → hardware properties → “Random hardware addresses” → Off for networks where MAC filtering is in use.

ISP-provided router limitations

ISP-provided routers (the box your internet provider gives you) often have more limited DHCP configuration options than aftermarket routers. Some ISP routers have small fixed DHCP pools (as few as 20 addresses), no way to adjust lease time, and limited logging. If you’re hitting the pool limit with an ISP router and can’t expand it: adding a separate router (in “access point” mode, not router mode) behind the ISP router gives you full DHCP control on the new router.

Don’t put a second router in router mode behind the ISP router without configuring it correctly — this creates a double NAT situation that causes connection problems for many applications. Use “Access Point mode” or “Bridge mode” on the second router so it handles Wi-Fi and DHCP without doing a second layer of NAT.

DHCP on corporate and managed networks

In office environments: DHCP is typically served by a Windows Server (DHCP Server role) or a network appliance, not the router. DHCP configuration is managed by IT. Common enterprise DHCP issues:

• Scope exhaustion: IT needs to expand the DHCP scope or add another subnet
• Rogue DHCP server: someone plugged in a router that’s handing out conflicting IPs — shows up as devices getting 192.168.0.x addresses instead of the corporate 10.x.x.x or 172.16.x.x range
• DHCP failover issues: enterprise DHCP often has a primary and secondary server; if they lose sync, lease assignment becomes inconsistent

For corporate network DHCP issues: report to IT with the affected device’s MAC address and the IP it received (or failed to receive). IT can trace the issue in DHCP server logs quickly once they have the MAC and timestamp.

The most important first step remains: confirm whether it’s one device or all devices. That single check splits the troubleshooting into two completely different paths and prevents spending 20 minutes reconfiguring a router when the problem was a single device’s stale DHCP lease all along.

DHCP relay and complex network setups

In setups where the DHCP server is on a different subnet from the clients (common in larger homes with multiple VLANs or in any managed network environment): DHCP relay agents forward requests between subnets. If the relay is misconfigured or the path between client and DHCP server is blocked: clients get no response and fall back to APIPA.

Signs you’re dealing with a DHCP relay issue: devices on one VLAN or network segment can get IPs, devices on another can’t, and the network is managed (you have switches with VLAN configs, or a separate access point with a different SSID). DHCP relay configuration lives in the switch or router firmware and requires knowing which interface connects to the DHCP server. This is IT territory on managed networks; on home setups, relay is rarely needed and the simpler single-subnet approach avoids this complexity entirely.

Manual IP configuration as a temporary fix

If DHCP is broken and you need network access immediately while you fix it: configure a static IP manually on the device. On Windows 11: Settings → Network & internet → Wi-Fi → your network → Properties → IP settings → Edit → Manual → IPv4 → On → enter an IP in the router’s range (e.g. 192.168.1.200 if the router is at 192.168.1.1), subnet mask 255.255.255.0, gateway = router IP, DNS = 8.8.8.8.

This bypasses DHCP entirely and gives the device connectivity while you fix the root cause. Ensure the manually-assigned IP is outside the DHCP pool range so there’s no conflict with future DHCP assignments. Once DHCP is working: switch the IP settings back to “Automatic (DHCP)” so the device returns to the normal managed configuration.

Router firmware and DHCP bugs

Some router firmware versions have known DHCP bugs — pool exhaustion at fewer than the configured number of leases, DHCP service crashing after a specific number of requests, or DHCP not recovering after the router comes back from power loss. If DHCP problems recur regularly despite no obvious cause:

• Check for a router firmware update (router admin → Administration or System → Firmware → check for updates)
• Factory reset the router and reconfigure from scratch (eliminates corrupted DHCP lease table)
• If the router is old and no firmware updates are available: replacement often makes sense — consumer routers older than 5-7 years have outdated security and limited support

A factory reset clears the DHCP lease table along with all configuration. After resetting: reconfigure the SSID, password, DHCP pool, and any reservations from scratch. This is time-consuming (30-60 minutes) but eliminates any firmware state corruption that partial configurations and power cycles don’t fix. Worth doing when a router has had recurring inexplicable DHCP issues despite other interventions being correct.

DHCP problems feel like big networking issues but usually have simple causes. The DHCP client list in the router admin panel — showing every active lease, its MAC address, and its assigned IP — is the single most informative view for diagnosing both single-device and whole-network DHCP issues. Checking it first, before any configuration changes, usually reveals the cause immediately. You might also run into Internet Keeps Cutting Out.