Nighthawk M5 SSH impossible

[chirofrance]

Hello, I desperately tried to connect a synology NAS behind the M5 for a system backup in SSH. But nothing works (it worked with a fiber connexion):
IP passthrow does not work (at least it allows a synology router to retrieve the address from the provider, but the ports are blocked to the outside.)
Port forwarding does not work.
Just like port filtering.
VPN passthrow is useless (enabled or not the VPN pass!)
UPNP is not recognized by synology devices
The DMZ also does not allow SSH connections to pass.
Does anyone have a solution?
THANKS

[JohnPeng]

Most likely the carrier doesn't allow remote access to the network behind the M5. Usually, they provide the VPN service for business customers as a subscription service.

Thanks