Problems with the Network

Check whether <Confirm Network Connection> is set to <On>.
<Confirm Network Connection>

If a dial-up router is on the network to which the machine is connected, the machine connects to a destination other than the intended destination, depending on the settings of the machine or dial-up router. This may result in subscriber line charges and call charges. Check the following.

If the dial-up router does not have to send packets via broadcast, change the router settings to ensure that it sends packets via a method other than broadcast. If it is necessary to allow broadcasting with the dial-up router, check whether an unnecessary destination is set.

Check whether the host name and IP address of the file server and mail server, etc. set in the machine are correct.

If the DNS server is on an external server, use the IP address instead of the host name for the destination, even when connecting to devices on the same network as the machine.

If the DNS server is on the network that the machine is connected to, check whether the information for devices connected to an external network is registered on the DNS server, and whether it is correct.

If the IP address of the computer where the Remote UI and utility software are executed is not allowed for sending and receiving in <Firewall Settings>, the information for the machine cannot be displayed on the computer. Check whether the settings are correct.
Specifying IP Addresses in Firewall Settings

When using device management software, set [Use Dedicated Community] to [On] and select [Read/Write] for [MIB Access Permission]. Also set [Use Dedicated Port] for [Dedicated Port Settings] to [On].
Monitoring and Controlling the Machine with SNMP

The machine cannot be recognized when utility software is used to access the machine with a community name other than the SNMP community name set in the machine. Check the SNMP community name.
Monitoring and Controlling the Machine with SNMP

If the message "An error has occurred." is displayed in the Web browser and the Remote UI cannot be started, invalid cache data may remain. Clear the cache of the Web browser.

If the machine enters the Sleep mode, it may not be able to be recognized from a computer. Cancel the Sleep mode or change <Sleep Mode Energy Use> to <High>.
Energy Consumption in the Sleep Mode

If you set a TLS version that is not supported by your operating system or software such as the browser, the machine cannot connect to the network using TLS encrypted communication
Upgrade your operating system and software, or lower the TLS version until connections are possible. However, if you lower the TLS version, connections may not be sufficiently secure.
Configuring the Key and Certificate for TLS