According to the syslog, it was not related to the PPPoE program, probably is the port negotiation rate (compatible) issue of the ONT to Brume2, which could prevent the Brume2 WAN up.
- Please try to replace the new/high quality network cable.
- If no luck, try to set the second LAN port as WAN, to see if it is compatible issue of the 2.5G port. Do them in the SSH:
uci set network.@device[2].name='eth1'
uci set network.wan.device='eth1'
uci set network.@device[0].ports='eth0'
uci set network.@device[1].name='eth0'
uci set board_special.network.wan='eth1'
uci set board_special.network.lan='eth0'
uci commit network
uci commit board_special
reboot