I just purchased an Archer AX21 router, and when setting up as per the included instructions, the router turns on the power, both wifi, and the internet LEDs. The internet LED turns orange and then the router starts continuous power cycles. During these cycles, I cannot access the web management site via ethernet nor connect to any wifi. If I disconnect my modem from the router, the router no longer power cycles and I can access the web management site.

This siatuation is similar to the one discussed in this forum post. I attempted the proposed solution by disconnecting the coaxial cable from the modem, but the power cycling still occurs when the modem is connected to the router without a coaxial connection. My firmware is the latest available as well. I have also tried to clone my PC's MAC address in the router in case my ISP has a MAC binding issue, but this did not resolve the problem. My old router, a TP Link WR841N works with no issues with the same modem.

Any suggestions on next steps prior to initiating a return of the router would be appreciated!