Your smart plugs go offline, your camera drops its stream, and your voice assistant reports lost devices — all at almost exactly the same time, every day. If you set a stopwatch, the gap between events is 24 hours to within a few minutes. This is the classic DHCP lease expiration pattern and it is one of the most-diagnosed and most-misunderstood connectivity issues on smart home forums. The fix does not require a new router. It requires understanding what your router is actually promising your devices, and why some devices misinterpret the promise.
What DHCP lease expiration is supposed to do
When a device joins your network, your router hands it an IP address with a lease time. The lease is a promise: “you can use this IP for 24 hours.” At half the lease time (renewal timer, or T1), well-behaved devices ask the router to renew the lease. Almost all renewals succeed silently, and the device keeps the same IP.
Problems arise from two places:
- The device’s networking stack is asleep at the renewal moment and does not send the renewal request until the lease is fully expired.
- The router, upon receiving a late-renewal or new-lease request, offers a different IP than the one the device had (because it re-allocated the old one to another device in the meantime).
When either happens, the device briefly loses its IP, has to negotiate a new one, and every open TCP connection dies during the transition. For devices that maintain a persistent connection to the cloud (cameras, video doorbells, hubs), that connection breakup shows as “offline” in the app for a few seconds to a few minutes, until the device retries.
The diagnostic that confirms DHCP is the cause
Two observations, taken together, confirm the pattern:
- The offline events happen at almost the same time each day. If the times drift consistently by a few minutes per day, DHCP lease is the culprit. If they are random, another cause is at play.
- The router’s DHCP lease time is set to 24 hours (the consumer-router default) or 12 hours (some ISP-supplied routers).
Log into the router and find the DHCP settings. On most consumer routers, the path is Network, LAN, DHCP Server. Note the lease time. If it is 86400 seconds (24 hours), 43200 (12 hours), or something equally short, and your offline events cluster around a specific time of day, DHCP is confirmed as the cause.
The three real fixes
| Fix | What it changes | Best for |
|---|---|---|
| Extend the DHCP lease time to 7 days | Devices renew a fifth as often, drop windows are less frequent | Small home network, low device turnover |
| Assign static IPs to critical devices via DHCP reservation | Router always offers the same IP to that device’s MAC address | Cameras, hubs, and devices that need to be found by IP |
| Reduce DHCP scope so old leases free up naturally | Router has fewer IPs to shuffle | Not usually needed on home networks with fewer than 50 devices |
DHCP reservations are the right answer for anything you care about. They give a device the same IP forever without configuring anything on the device itself. On any modern router, the flow is:
- Router admin, DHCP Server, Reservations (or Address Reservation, or Static Leases).
- Find the device in the connected-clients list. Note its MAC address.
- Click Reserve or Add Reservation. Enter the MAC, choose an IP in the DHCP range (or slightly outside, if the router allows), and save.
- Reboot the device to force it to pick up the new lease immediately.
The devices that specifically misbehave on DHCP renewal
Not every device drops when its lease renews. Well-implemented stacks renew smoothly. These are the classes that struggle:
- Cameras with persistent cloud tunnels. Wyze v2, older Nest Cam wired, Reolink E1 series. The connection to their cloud breaks when the IP changes even by one octet, and the reconnect takes 15-60 seconds.
- Smart plugs based on the Tuya cloud. Many rebranded Tuya plugs (Gosund, Teckin, some TP-Link Tapo) drop their cloud connection when the IP changes and can take up to 5 minutes to re-establish.
- Smart lock Wi-Fi bridges. August Wi-Fi Bridge, Yale Access Bridge. When the bridge’s IP changes, the lock is inaccessible remotely until the bridge re-registers.
- Cheap smart speakers. Some no-name Alexa-integrated speakers on the low end of the market.
Devices that generally do not drop on lease renewal: Nest thermostats, HomeKit-native accessories, Hue Bridge, most Zigbee devices (because they do not use Wi-Fi), Google Nest Cam battery, Ring Doorbell 4 and Pro 2.
The gotcha with static IP set on the device itself
Owners sometimes bypass DHCP by setting a static IP directly on the device (in its app or admin panel). This works, but has two downsides:
- If your router’s DHCP range covers that IP, the router may hand the same IP to another device that arrives later. Two devices with the same IP is silent chaos.
- You have to remember to change the device’s static IP if you ever change your router’s subnet, which most people forget.
DHCP reservations avoid both. The router remains the source of truth for IP assignments, and the device does not need any configuration.
Frequently asked questions
Should I set my DHCP lease to infinity? No. Router DHCP servers do not support infinite leases in most consumer firmwares, and even where they do, the router forgets the lease on reboot. Seven days is a reasonable ceiling.
Does a DHCP reservation guarantee the device gets the same IP forever? Yes, as long as the device’s MAC address stays the same and you do not delete the reservation. See the article on MAC randomization for a related complication.
Why does my router’s connected-devices list show a device I removed months ago? Some routers keep DHCP lease records long past the lease expiration for troubleshooting. Delete the entry manually in the DHCP section.
Can I run DHCP on my own machine (not the router)? Yes, using isc-dhcpd or dnsmasq, but you must turn off DHCP on the router first. Two DHCP servers on the same subnet is a hard-to-diagnose failure.
Does IPv6 have the same issue? IPv6 uses SLAAC (Stateless Address Autoconfiguration) or DHCPv6, and lease renewal behavior differs. Most smart home devices are IPv4-only today, so this issue is IPv4-specific.
