Hi Patrick
As written in the manual, the devices is displayed only if the type of authentication defined in the domain is not PPPoE, the type of HGW is “Mikrotik” and it is reachable over the network from HSNM and you have defined, in the data of the HGW, the following fields: IP address; Admin password.
If there is a possible firewall, the ports 23 and 8728 must be open