I currently have the typical setup where I connect my PC devices to an AX73 router, which is connected to an ONT modem using cables. I have been using this router for over a year without any issues. However, after my ISP upgraded my internet speed to a 500Mbps plan, I noticed that whenever I try to download a large file at its full speed of around 62Mbps, the router loses its internet connection for exactly 1 hour. Internet connection works fine afterwards.

During this disconnection period, I am still able to access the router management page through my browser. I have attempted to resolve the issue by rebooting the router and ONT modem, as well as connecting my PC directly to the ONT modem, but these attempts have been unsuccessful. I've also tested in different day, I directly connect my PC to the ONT modem and download the same file at the full speed of around 62Mbps, there is no internet disconnect. This seems to indicate my router is the culprit.

As a temporary solution, I have set a speed limit of 30Mbps to avoid the disconnection issue. I'm at a loss here as to why this is happening and need your help.