When I use Network Discovery in the Managability Commander tool via VPN into a certain network, my AMT computers are not discovered. When I add a known AMT IP from this network to the computer list it adds correctly and I can connect to it. However, even if I know the IP and scan the range including the IP I get no discovery results. Using the web tool, I can also connect to a AMT box on the problem network via 16992 with no difficulty. The only problem I seem to have is with non functioning Network Discovery on the problem network. I have used Network Discovery on my local network and VPN'd into other remote networks and it has been successful in the discovery effort. But on this particular network, no luck. I assume it is not a firewall issue because I can connect to 16992 using the Web tool. It is happening on more than a single computer so I assume it is not an issue on the target computers. Help!
This sounds like a network-specific issue with the way the Manageability Commander Tool operates. For the Network DIscovery feature, the Manageability Commander Tool performes a "staged / phased" approach by performing the following order of operations:
Without knowing the specifics of the network configuration you are working with, the most likely cause of this issue is that the ICMP (ping) packets are being blocked by either a firewall or router/switch configuration. This would prevent the Manageability Commander Tool from being able to detect a viable endpoint at a given IPv4 address. However, as you are experiencing, direction connections to manually entered IP addresses still work as only the ping packets are being blocked.
I have no problem manually pinging computers on the problem network. In fact that is how I located the AMT unit, I manually pinged all addresses within the DHCP range to identify active computers and then for each active computer I manually attempted to make a AMT connection. When I succeeded I then knew the IP of the AMT computer. Pings are not being blocked, yet the Management Commander Network Discovery tool is not working for me.