A method for a power-saving operation of a subscriber line (100.1) terminated by an access interface (23.1) implemented in a customer router and by a port (51.1) implemented in an access network device, the customer router further comprising a wireless network interface configured to communicate via a wide-area wireless network with a network device using a wireless network protocol, wherein the method comprises the steps of: a) deactivating the port (51.1) of the access network device in response to a time scheduler and/or in response to a predefined event, which is detected by the access network device; b) activating the port (51.1) deactivated in step a) by b1) transmitting, by the customer router, a request message for activating the deactivated port (51.1) of the access network device via its wireless network interface to the network device; b2) generating, at the network device, a port activating signal in response to the request message of step b1); b3) transmitting, by the network device, the port activating signal generated at step b2) to the access network device, and b4) activating, by the access network device, the port deactivated at step a) so that the subscriber line (100.1) will become available for data transmission between the customer router and the access network device, wherein the wide-area wireless network is a low-power wide-area radio network, LPWAN, and the wireless network interface of the customer router is a low-power radio network interface configured to communicate via the low-power wide-area radio network LPWAN using a low-power wide-area network protocol. a) deactivating the port (51.1) of the access network device in response to a time scheduler and/or in response to a predefined event, which is detected by the access network device; b) activating the port (51.1) deactivated in step a) by b1) transmitting, by the customer router, a request message for activating the deactivated port (51.1) of the access network device via its wireless network interface to the network device; b2) generating, at the network device, a port activating signal in response to the request message of step b1); b3) transmitting, by the network device, the port activating signal generated at step b2) to the access network device, and b4) activating, by the access network device, the port deactivated at step a) so that the subscriber line (100.1) will become available for data transmission between the customer router and the access network device, wherein the wide-area wireless network is a low-power wide-area radio network, LPWAN, and the wireless network interface of the customer router is a low-power radio network interface configured to communicate via the low-power wide-area radio network LPWAN using a low-power wide-area network protocol. b1) transmitting, by the customer router, a request message for activating the deactivated port (51.1) of the access network device via its wireless network interface to the network device; b2) generating, at the network device, a port activating signal in response to the request message of step b1); b3) transmitting, by the network device, the port activating signal generated at step b2) to the access network device, and b4) activating, by the access network device, the port deactivated at step a) so that the subscriber line (100.1) will become available for data transmission between the customer router and the access network device, wherein the wide-area wireless network is a low-power wide-area radio network, LPWAN, and the wireless network interface of the customer router is a low-power radio network interface configured to communicate via the low-power wide-area radio network LPWAN using a low-power wide-area network protocol.