A Linksys router red light represents critical faults, including the absence of an internet connection, a defective device, or a failed connection with the modem. Loose cable connection, outdated firmware, ISP outages, or an internal router error could be the reason behind this problem. For troubleshooting, first please verify all physical connections, reboot the router and modem,m and verify your internet service is active. Just in case the problem is still not fixed, you can try doing a factory reset and see if it helps out with fixing the red light issue, you can also update the router’s firmware. Only identifying the cause is the initial stage to get your Linksys router” ‘s silky smooth performance back.