How to configure workers running at VMs behind PROXMOX

[eichher]

I want to run several workers at a PROXMOX virtualization host in the Cloud. Cronicle master is at the local network and I have only one IP address to access the PROXMOX host (but I can reach the VMs by configuring different ports via NAT). I installed a worker at one of the VMs and added it manually at the master server. I got connection, but the delievered ip address from the worker was the address of the PROXMOX internal network and server definition was greyed out. I changed the ip address manually in the json file of the master server, now the worker is active and can be used. But there is no way to add a second worker for the PROXMOX environment, because I have only a single ip address. I can redefine the worker port at the client VM in the config.json file, but I cannot add the worker to the master server, because the master server throws an error "Server is alreay in cluster". Is there a way to add a port definition for a worker at the master host?