Ethernet connection identified, but no internet access

[is2oliviaid]

These days, the router got unplugged and stopped working, but we fixed the WiFi. My PC, connected via Ethernet through a power-line adapter, still has no internet access.
I've tried flushing the DNS, resetting IP settings, restarting the router, modem, and PC, using the network reset button, running the troubleshooter, updating drivers, switching Ethernet cables, and connecting directly to the modem.
The troubleshooter reports errors like DNS server isn't responding,The default gateway isn't available and the connection between your access point, router, or cable modem and the internet is broken, but these issues sometimes show as resolved without fixing the problem.