Question: How to access device behind a VPN client router

[surveylancer]

I would like to know f there are methods/configuration to access device that is sit behind the VPN client router.

Setup diagram as shown below:


Routers are configured as VPN clients and connected to the OpenVPN Cloud.

My Server is able to reach router setup webpage via VPN address. But I am not sure how to access device.

Is it possible to setup as port forward/port mapping, e.g: https://vpn_id001:8080, https://vpn_id002:8080, https://vpn_id003:8080, ... ?

I am hoping the local IP address of all routers and devices are kept as the same setup, e.g. 192.168.1.1 and 192.168.1.100