Can't connect to the internet from the LAN (Raspberry Pi 4)

I'm managing to get internet connection from the Pi itself. However, now I can't get any internet connection from the LAN PC.

From the logs, it tells me that PPPoE connects, and I can verify by sending pings to the internet from the Pi itself. However, the problem starts here:

Network device 'pppoe-wan' link is up Interface 'wan' is now up Reloading firewall due to ifup of wan (pppoe-wan) eth0: link is up br-lan: port 1(eth0) entered blocking state br-lan: port 1(eth0) entered forwarding state Network device 'eth0' link is up Bridge 'br-lan' link is up Interface 'lan' has link connectivity eth0: Link is down br-lan: port1(eth0) entered disabled state Network device 'eth0' link is down Bridge 'br-lan' has link connectivity loss Network device 'eth1' link is down Interface 'wan' has link connectivity loss

Any idea what's the issue here?