Internet not working after power outage (Japan, NTT VDSL + TP-Link router)

Hi everyone,

My friend in Japan is having an issue with their internet after a power outage. The setup is:

– NTT VDSL modem → TP-Link router → PC

– After the outage, there is no internet connection

Here’s what we found:

– The modem shows normal lights (VDSL link is up, no alarm)

– The TP-Link router WAN is set to PPPoE

– It shows: “Authentication failed (username or password incorrect)”

– WAN IP is 0.0.0.0

– If we connect modem → PC directly, there is also no internet

We are not sure if:

1. The router lost PPPoE credentials after reset
2. The modem is in bridge mode or router mode
3. The ISP (NTT) requires re-authentication after outage

Questions:

– Is this most likely just missing PPPoE credentials?

Thanks in advance