In the Wireguard section of the manual
I think the last section should be titled “Visit Client’s LAN Subnet from WireGuard Server LAN Subnet”
Also "Add a line to the end of the Server’s config file of the Client’s subnet you want to visit. For example, if the LAN subnet of the Client is 192.168.11.0/24, then the line to add to the /etc/config/wireguard_server is
list subnet ‘192.168.11.0/24’