Question about Huawei B315

The Huawei router will be assigned a Dynamic IP as soon as it connects. Your VPN router would have to be registered with a dynamic DNS service so that this address can be reached from outside. In my experience, however, certain mobile providers block access to their own network. (I had this experience with my last attempt with Salt).

I mean VPN in both directions (I am not an IT specialist).
I can't get an external IP, but this is probably due to the provider and not the router.
Provider blocks the IP and you have to order a CAA service, Swisscom offers this service, Sunrise?

What do you mean by open VPN? IPV4 works.