Networked Ultimaker printers can connect to a local area network using either Wi-Fi or Ethernet. By default, when connecting to the local area network an IP address will be dynamically assigned to the printer.
The printer will receive a new IP address each time it connects to the local network. Therefore every time the printer reconnects to the network, for example after being switched off and on again, a new and potentially different IP address will be assigned.
Setting up static IP
Tip: S-line printers running firmware 6.1 and newer can import network settings, including static IP settings via USB. Read more about this here.
If you need a static IP address and your network is not supporting this by default, this would require a network configuration change assigning a fixed IP address to the MAC address of the printer. This is standard network functionality of a router, for more information please refer to your routers manual.
Read this guide to learn more about the MAC address of your printer.