Fujitsu ScanSnap N1800 Operator's Manual page 111

If the IP address is the same as one already in use, network communication
problems will occur. In this case, try the following steps:
1. Disconnect the LAN cable.
2. Press the [Shutdown] button on the LCD touch panel to turn the scanner
off.
3. Press the power button to start the scanner with the LAN cable
disconnected.
4. Enter a non-duplicated IP address.
5. Re-connect the LAN cable to the scanner.
When DHCP is set to [On], the following scanner settings are assigned by the
DHCP server:
IP Address
Subnet Mask
Default Gateway
DNS Server
WINS Server
Domain Suffix
Even if DNS or WINS server is set, priority is given to the scanner settings
over the DHCP settings.
The connection will be lost if the scanner's IP address is changed via the
network interface. To continue with other settings, login to the network
interface again. If connecting via an IP address, use the new IP address.
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