Remote Screen Sharing Suddenly Doesn't Work; All Ports Filtered

I am accessing a remote Mac over a VPN connection with a static IP address. I have the Mac setup to be woken up for network access, to never go to sleep anyway, etc., but sometimes (after days or weeks) it becomes no longer remotely accessible in a seemingly inexplicable manner. Yesterday, I was able to access it fine and it was working, then something changed over night, and now I am no longer able to access it and I am 2500 miles away. I was expecting to access it this week but cannot and cannot physically reset the connection.

When I run "nmap" to check port status I get the following:

nmap 128.111.225.208

Not shown: 996 closed tcp ports (conn-refused)

PORT     STATE    SERVICE

22/tcp   filtered ssh

445/tcp  filtered microsoft-ds

3283/tcp filtered netassistant

5900/tcp filtered vnc

The screen sharing app refuses to connect, and I cannot SSH given it is also filtered for some reason, despite . The Mac is on, as I can play sounds on it via the FindMy app, but when I try to connect in any other way, I get the following error:

"Unable to communicate with “128.111.225.208”.  Make sure the remote computer is available and the firewall is not blocking screen sharing."

I don't know why the vnc service sometimes suddenly switches to filtered. I do not believe this is a local firewall issue, but something internal with the Mac itself. Does anyone have any ideas if there is a way to access the machine or attempt to "wake" it (if indeed, for some reason, it is asleep, though I do not believe it to be since the FindMy seems to work), from a remote location?