@Kevin_Z as I what know, ISP will not enforce the static route to TP-Link router. The one who make the dial up internet connection is TP-Link router. If your environment is using Unifi, you can try...

@Kevin_Z Hi, the problem is resolved now. Just highlight to your technical team about this bugs. Below is the image, Thanks.

@Kevin_Z I found the bugs. Internet connection mode by default is set as Auto mode. It is because I changed the Network > Internet Settings > Connection Mode from "Auto" to "On Demand (0 Minutes)"...

@Kevin_Z Hi, yes.. Unifi profile in Archer A6 with same configuration. other AX20 user also using Unifi. I configured the Internet Connection Mode to On Demand with 0 Minutes. One of the person from...

@Kevin_Z hi, this 1.0.0.0/8 route is not happen every time, it randomly happens after I off and on the router. But most of the time, the 1.0.0.0/8 route will be there. I have to create a static route...

@Ivaylo im waiting, seem like no one from TP-Link want to entertain my issues.