A router's useful life is not tied to its firmware support. Even after a manufacturer stops issuing updates, the hardware will keep routing traffic as long as it functions. The risk is not immediate failure but the accumulation of unpatched security vulnerabilities.
Attackers frequently scan for vulnerable routers in bulk, conscripting them into botnets or using them to relay malicious traffic. That makes an outdated router a liability even if it is not singled out. The source advises treating the five-year mark as a checkpoint, noting that Netgear suggests a four- to five-year timeline for security updates.
Before replacing hardware, users should verify the exact model and hardware revision, install any final update, and disable remote administration. A strong, unique admin password is also recommended. For technically inclined users, custom firmware such as OpenWrt may extend support, but the source warns that a bad flash can permanently disable the device.