A method performed by a router connected to an Internet Protocol Version 6, IPv6, network and an Internet protocol Version 4, IPv4, network, the router comprising a first resource directory and a network address translation table, wherein the first resource directory is used as a repository for Internet of Things, loT, resources of the IPv6 network and implements the Representational State Transfer, REST, interfaces for registration, distribution, and lookup, of the IoT resources, the method comprising: receiving (S401, 750), from an IPv4 compliant device connected to the IPv4 network, a request for a set of all the resources of the IPv6 network, using the REST interfaces; transmitting (S402, 760) to the IPv4 compliant device, the set of all the resources of the IPv6 network in a payload message, using the REST interfaces; receiving, from the IPv4 compliant device connected to the IPv4 network, a request for an IPv6 network resource, comprised in the set of all resources, enabled by an IPv6 compliant device connected to the IPv6 network; obtaining from the first resource directory an external IPv4 address and an external IPv4 port number corresponding to the IPv6 network resource, the first resource directory comprising a name, a local IPv6 address, and a local IPv6 port, for the IPv6 network resource, the external IPv4 address, and the external IPv4 port number; creating an entry in the network address translation table for enabling communication between the IPv4 compliant device and the IPv6 network resource, the entry comprising the external IPv4 address, the external IPv4 port number, the local IPv6 address and the local IPv6 port number for the IPv6 network resource, and a local IPv4 address and a local IPv4 port for the IPv4 compliant device; and transmitting the external IPv4 address and the external IPv4 port number to the IPv4 compliant device. receiving (S401, 750), from an IPv4 compliant device connected to the IPv4 network, a request for a set of all the resources of the IPv6 network, using the REST interfaces; transmitting (S402, 760) to the IPv4 compliant device, the set of all the resources of the IPv6 network in a payload message, using the REST interfaces; receiving, from the IPv4 compliant device connected to the IPv4 network, a request for an IPv6 network resource, comprised in the set of all resources, enabled by an IPv6 compliant device connected to the IPv6 network; obtaining from the first resource directory an external IPv4 address and an external IPv4 port number corresponding to the IPv6 network resource, the first resource directory comprising a name, a local IPv6 address, and a local IPv6 port, for the IPv6 network resource, the external IPv4 address, and the external IPv4 port number; creating an entry in the network address translation table for enabling communication between the IPv4 compliant device and the IPv6 network resource, the entry comprising the external IPv4 address, the external IPv4 port number, the local IPv6 address and the local IPv6 port number for the IPv6 network resource, and a local IPv4 address and a local IPv4 port for the IPv4 compliant device; and transmitting the external IPv4 address and the external IPv4 port number to the IPv4 compliant device.