If a device is in the same subnet as your Lansweeper server, a MAC address will be retrievable merely by a successful ping. This is because the MAC address can be retrieved from the ARP table of your Lansweeper server itself in this case. Using the MAC address, the vendor can then be retrieved.
This unfortunately does not work outside of the subnet of your Lansweeper server. In those cases a protocol through which information can be retrieved needs to be available, such as SNMP. Which requires SNMP to be enabled on the device and the community string to be added and mapped under Scanning\Scanning Credentials. A full list of protocols through which Lansweeper can retrieve information can be found in the first paragraph of
this article.