DIAGNOSIS: The router is stuck in its boot or connection phase. That solid orange light on the front usually means it's powered on but hasn't established a proper internet connection from your modem yet.
FIX: This is almost always a handshake issue with the modem. First, power everything down. Unplug both the modem and router. Wait a full minute. Now, plug only the modem back in and wait until all its normal lights are stable (this can take 2-3 minutes). Then, plug the router back in. Make sure you're using the included Ethernet cable, and it's plugged from the modem's LAN or Internet port into the router's blue Internet (WAN) port. Give it another 2-3 minutes. The light should eventually turn white.
IF THAT DIDN'T WORK: Try a different Ethernet cable if you have one. Also, log into your modem's settings (if you can) and make sure it's in 'bridge mode' or isn't also trying to act as a router, which can cause an IP address conflict.
HEADS UP: If you're replacing an old router, the modem might be holding onto the old router's MAC address. A quick trick is to clone the MAC address in the AX55's admin panel under Advanced > Network > Internet, but try the power cycle sequence first—it fixes this 90% of the time.