Apologies if this has duplicate posted - my profile shows a post as having been made but it's not showing up.

Wondering if anyone has any advice to help me forward ports.

Set up is: ADSL2+ modem -> main deco M4 -> 2x other M4 units in mesh

Main computer is connected via ethernet to main deco and this is the computer I'm trying to port forward to.

The main deco unit shows an internal IP as its WAN so presumably there is a double NAT issue.

I have used the deco app to forward the appropriate ports to the main computer (and so also has a static internal IP). I have also opened the same ports to the main deco unit through the modem software, however telnet shows I cannot communicate through the ports I have tried to open.

I have tried making the main deco a DMZ host, tried turning off the modem firewall, have activated UPnP but still the ports are closed.

Any advice would be appreciated!