I use MeshCentral running on Debian on a small VM and then I access MeshCentral through the Web UI. If you have any Raspberry Pi's laying around that aren't being used, it would be a great candidate for that type of setup.

So I have a 3-node cluster of optiplex 5060 micros with i5-6800. I have AMT enabled on a different VLAN from the hypervisor I have running and it works great for remote management. One thing to keep in mind that for the KVM access to continue to work, I had to add an HDMI dummy plugs to keep the display working after reboots. All of the other functions associated with AMT worked after reboots.

For your other questions: ATM would only be accessible from the network you have it running on without any firewall rules/port forwarding/NAT

Yes reset it to factory. Turn ATM off and reset it.

I forgot to mention that with those solutions I used port 2525 for incoming and outgoing.

If you are saying you can’t because your ISP blocks port 25 there are a few solutions that you can use that are free as long as you don’t send or receive over 2000 emails a month or something like that. I have used both of these solutions with my last ISP since they blocked port 25. I used http://ghettosmtp.com as a relay server. Wesley, the provider of the service is a pretty neat guy. I used https://www.smtp2go.com as my external outbound relay. They both worked great as a work around. I have ATT fiber now and 25 was blocked until I called in and requested it to be unblocked.

Anyways, I hope that helps. Let me know if you have any questions!

This app is freaking incredible! Hariette, your hard work has paid off. Thank you so much!!