? No Terminal access to docker images ?

To prepare a migration to IRIS I use Docker images.
The (aged) application is built around Caché Terminal
And on Windows,  IRIS uses the same ctelnetd.exe as Caché.

In my Docker installation, Telnet Settings are just grayed out in SMP.
and my Terminal can't 'connect.
Port mapping is OK and verified with TCP

Working from the console in Docker  with the whole set of ESC and
screen formatting is not acceptable.
We tried WebTerminal but there is just no Partition behind as in Terminal.

How can I switch on Telnet support in the Docker image?