externel ip:port not reachable from inside behind nat

[eb8]

hello,
I'm struggling with with a "simple" setup.

vmbr0 has ext-IP
vmbr1 is nat

LXC is connected to vmbr1 only
portforwarding from outside is working

the service within the LXC needs to check the availability of the configured ext-IP an tries to reach it's port(forwarding) -> does not work, (same with nmap)
what would be necessary to configure, that the service can check it's Port on the ext-IP?

TIA
guenter

 

[Alwin]

Needs to be done form the outside. And why would the destination (CT) need to check this?