Diagnosis
That solid red light on the front means the router isn't getting a valid internet signal from your modem. It's almost always a physical connection or modem handshake issue.
How to Fix It
First, power everything down. Unplug your modem and the router. Wait a full minute. Plug the modem back in and wait for all its lights to stabilize. Now, plug the router back in. Make sure you're using the yellow WAN port on the router and a known-good Ethernet cable to connect to your modem. Give the router a few minutes to boot; the red light should eventually turn white.
If That Didn't Work
Log into the router's web interface (192.168.50.1). Go to the WAN section under Advanced Settings. If your ISP requires specific connection types (like PPPoE) or VLAN tagging, you'll need to enter those details here. For most people, leaving it on Automatic IP should work.
Heads Up
Some modems are picky and need a full power cycle of their own to recognize a new router. If you just swapped from an old router, a longer modem reset (like 5 minutes unplugged) can clear its old MAC address binding.