I recently buy a new modem/router tplink VR400 to replace my stock modem from ISP, I've set the VR400 in bridge mode just like my old modem and it work when I test the connection on my PC. But it fail

After a relatively easy setup yesterday, I came home after a night shift to discover the main deco unit was flashing red. I figured a quick restart would solve the issue. Alas. No matter what, the uni