Sets EnableICMPRedirect = 0 under Tcpip\Parameters. By default Windows lets inbound ICMP redirect packets alter its routing table — a legitimate router feature, but also a vector an attacker on your network can use to silently reroute your traffic. Disabling it means only your real gateway controls routing. No effect on normal browsing/gaming. Reboot required. Reversible.
MaxTweaks applies this tweak with one click and snapshots your original setting first, so you can revert it cleanly at any time. A System Restore point is offered before batch changes, and every tweak links to its official source.
Get MaxTweaksOfficial documentation: https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/tcpip-and-nbt-configuration-parameters