Fixed IP addresses for your smart home, managed in one place

After a ten-second power cut your doorbell is offline, your printer has vanished and your wall tablet has logged itself out. Nothing is broken. Your devices simply picked up different IP addresses, and every integration that binds to one of those addresses is still looking at the old one. There are more of them than you would guess: cameras over an RTSP URL, your washing machine with its local API, the printer over IPP, the tablet that signs itself in.

Reserve, do not set by hand

You can type a static IP into every device, but use a DHCP reservation in your router instead. It is barely more work and it saves you a great deal of hunting later:

• Every address lives in one place, in your router admin.
• You can no longer hand out duplicate addresses.
• Replace a device and you only edit the reservation, without logging into anything.

In UniFi you open the client and pick Settings → Fixed IP Address. Keep to a fixed block outside the dynamic range while you are at it, for instance .10–.49 for infrastructure and .50–.99 for smart home devices. A year from now you will still know where something belongs.

Which devices need a fixed address

• Home Assistant itself
• Cameras and the doorbell (streams and events)
• Devices with a local API: washing machine, printer, air conditioning modules, media players
• Wall tablets that sign in automatically over trusted networks
• NAS and print server

You can skip lights and sensors on Zigbee, because they have no IP address at all. They all go through the coordinator.

Keeping trusted networks safe

If you let a wall tablet sign in automatically through trusted_networks, restrict that to the single fixed address of that tablet and tie it to one user without admin rights. Otherwise you hand a key to your house to anyone who can take over that address. Put addresses and user IDs in secrets.yaml so they never reach your version control:

homeassistant:
  auth_providers:
    - type: trusted_networks
      trusted_networks: !secret wandtablet_ip
      trusted_users: !secret wandtablet_users
      allow_bypass_login: true
    - type: homeassistant

Write it down

Keep a list of which address belongs to which device, either in your router or in your HA repository. It feels excessive right up until something breaks, and then it saves you an evening.

Frequently asked questions

Should I enter the IP address on the device as well? No. With a reservation the device always gets the same address over DHCP. Setting it on the device by hand is actually more error-prone, because you can then forget it in two places.

What if two devices end up with the same address? That cannot happen as long as you keep your reservations outside your DHCP server's dynamic range, because your router will never hand those addresses out itself.

How does this relate to VLANs? Each VLAN has its own address range, so reserve addresses per VLAN. A separate IoT VLAN covers how to divide up your network. A fine example of a device that genuinely needs a fixed address is the washing machine with a local integration.