Even though the wan cable is plugged in, it does not appear in the switch section. Default settings are this. Is this normal?
TP-Link Archer c60 v2
Some CPUs used in routers have multiple (internal) ethernet ports that are individually routed (i.e. not pat of the switch). In those cases, sometimes the wan is directly connected to the CPU on one ethernet port, and then another internal port is connected to the swtich chip.
Since your device is swconfig based, the best way to know for sure is to to evaluate the /etc/config/network file. Post that here and we can verify.