Is it possible to get a remote client to send a DHCP-style request to a server (which you're on) to test the network routes are open? I can check from server to client, but different ports are used on the opposite direction (i.e. client to server). We're trying to avoid RDP-ing into the client to do this test.
On *nix-based machines, way to go is dhcping:
dhcping -h CLIENT_MAC_ADDRESS -c CLIENT_IP -s SERVER_IP
you'd have to setup a fix address on the server, of course.
On Windows machines there's also a handy tool: