Cant access VIA 192.168.0.239

As per the NETGEAR ProSAFE Managed Switches M4100 Installation Guide it depends if there is a DHCP server reachable from the switch (which will assign an IP address), otherwise it will fall back to 169.254.100.100/16

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Perform the Initial Configuration
You can manage your switch through its web management interface or
by using the command-line interface (CLI) through a console port. This
guide shows you how to configure your switch using the web management
interface. It also covers using the CLI to determine a DHCP-assigned IP
address or using ezconfig to assign a static IP address. For more information
about CLI management, see the CLI reference manual and software
administration guide on the resource CD.
To configure your switch using web management, use one of the following
procedures, depending on how your Windows computer is set up:
• Computer in DHCP Client Mode Without a DHCP Server.
• Computer with a Static IP Address.
• Computer in DHCP Client Mode with DHCP Server.
Computer in DHCP Client Mode Without a DHCP Server
The switch assumes a default IP address of 169.254.100.100 and a
subnet mask of 255.255.0.0. The switch is in the same subnet used by the
computer NIC port when in DHCP-client mode without a DHCP server present.
Use this IP value to log in to the switch.

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