remote connection and graphic problem I  need to be able to remote control many headless (without monitor) macs.
All the macs are on different locations, on different networks and with different router settings.
These are the informations i have at any moment about every machine: 


Computer name 
Local IP Address
Public IP Address


BUT I cannot access the router confirguration those devices connect to (for, like port forwarding).

I tried several free services (my company does not want to spend money on commercial applications) like Chrome Remote Desktop and DWService but hey all have problems rendering the pages.

Since the macs are headless, the graphic card does not kick-in, resulting in a lot of white windows and many GUI being unavailable (like many elements of the menubar)

I could use HDMI dummy plugs that simulte a monitor, solving the issue of blank windows, but still that would require my company to spend ~6 $ for each machine and they asked me to find a solution, if there is, to do that without extra hw.

I spent the last three days finding for a solution, without success.
But maybe some of you guys can direct me to a solution, if there is one!

Thanks!
Buy the dongles. I worry your company is able to secure these if it isn’t budgeting for training and support let alone very inexpensive adapters. 

There’s being frugal and then there’s “we’re not even thinking about selling one Mac” to fund to what needed to run the rest of the fleet. 

If your labor is cheap, make cakes and cookies and sell them to fund your business. Good luck, I don’t mean to insult, but the reasoning in your question doesn’t add up. 

Also, solve your network issue - the business and you are toast if you can’t get control of the network (we’re back to security and priorities).