This could be because of the option mentioned above, a firewall or a change in configuration of the VPN link. My best guess to answer the question is that for some reason the ARP requests or responses are not sent through the VPN link. This method is off by default and can be configured if your router has this information.
The Router SNMP MIB query works by querying router's .atTable or. for IP-to-MAC-address mappings. You can scan IP addresses within any range, as well as ports. Angry IP Scanner is probably the fastest port and IP address scanner around.
For this article, I’m using the Windows 10 variant of Angry IP Scanner. With Angry IP Scanner you can scan your network from a Mac computer and access all sorts of data about the latter. It helps you to scan a range of IP addresses to find live hosts, open ports, and other relevant information of each and every IP address. Angry IP scanner can resolve NetBIOS protocol, computer names, workgroup name, currently logged in users. It is cross-platform and lightweight where it can be installed easily. This is what gives you some MAC addresses. Angry IP Scanner is a free, lightweight, cross-platform, and open source tool to scan networks. Angry IP scanner is a very fast IP address and port scanner which is popular amongst systems administrators. The NetBios request is a regular UDP packet that works in VPN, however it will only resolve the MAC address on the devices that implement this protocol. You can try ticking the Allow ARP outside current subnet option in the scanner, though granted Angry IP scanner did not work, this wouldn't work either. Other interesting Mac alternatives to Advanced IP Scanner are Angry IP Scanner (Free, Open Source), Zenmap (Free, Open Source), MASSCAN (Free, Open Source) and Fingbox. The app can also detect the ports a computer has open. The program scans a specified range of addresses and shows the IPs of the computers from which it receives responses, regardless of what operating system they use.
The ARP works well in a LAN subnet, but is not usually transmitted over a VPN link. If that doesnt suit you, our users have ranked more than 25 alternatives to Advanced IP Scanner and 16 are available for Mac so hopefully you can find a suitable replacement. Angry IP Scanner is a practical tool to retrieve the IP addresses of all computers connected to a specific network.
Generally there are 3 ways the scanner uses to determine target MAC addresses: