Hairpin Nat not working with PPPOE Server & Clients

I manage a small Wisp and have been working on Mikrotik for close to 12years now so I know my way around and I understand most routing and networking princeples.

The problem I have is being able to have local clients(PPPOE Clients) all on a shared public IP being able to access services on on other PPPOE Clients on same shared Public IP and services inside our ISP network.

I can provide a small example should you require this as well as the export of the router we are having the issues on.
I would want to know how the problem would be resolved as I like to learn from problems as I believe that is how we can understand.

I added a small drawing to show somewhat the setup.

The Issue:

PPPOE-CLIENT 1, 2, 3 cannot access the RDP server connected to Client HQ MT.

PPPOE-Client 1,2,3 & Client HQ are natted through the x.y.z.2 gw on the Wisp #2 Router, but for some reason I cannot seem to get the Hairpin Nat to work.

I have just added the RDP server as an example there are more that 1 service / device that these PPPOE-Cliens 1,2,3 must be able to acces but I think if I can get the RPD working I can just Implement the same or tweak the Hairpin nat to be able to reach those services.

Should You require more info please let me know…
Your help would be greatly appreciated and I look forward to learning from your expertise.

Thank You
Kind Regards
Drawing2.pdf (166 KB)

A simple

/ip firewall nat add chain=srcnat action=masquerade src-address=172.16.253.0/24 dst-address=172.16.253.0/24

should do the trick.