in LuCI (System - Starup) is the main service control - via the ssh directory: /etc/init.d
If the service is enabled when restarting the router, it will have status Enable - via the ssh directory: /etc/rc.d
Then is specified (in our case UPnP and check box) for other purposes (other services) - via ssh edited file bold marked /etc/config/upnpd:
option enabled '1’
option enable_natpmp ‘1’
option enable_upnp ‘1’
option secure_mode ‘1’
option log_output ‘0’
That is, to have the service running, you must have Enable in both places - I would not discuss it further.