Route NAT'ed Subnet through OpenVPN

[piffpaff34]

Hello together.

I have a public server with a running Hyper V instance. The server is reachable by a single public IPv4 address, lets say 88.99.1.1

The VMs are in an own subnet and bound to the hyper-v's Internet connection by a Hyper-V NAT-Switch I configured via Powershell. This NAT Switch has 192.168.100.1, so his subnet is 192.168.100.0/24.
The VM's can connect to the internet and ping the Hyper-V Host without any problems. The Hyper-V-Host also can ping the VM's.

The Hyper V Host has an OpenVPN-Server installed that's supposed to be connected by its clients. This works actually.

My intention is to bring the OpenVPN-Clients to the VM's and their NAT'ed network and that's what I'm not able to get working. I tried different configurations but couldn't get it working. Who can help me?


Here are my configurations:

Server:

port 1194
proto udp4
dev tun
ca "C:\\Program Files\\OpenVPN\\ovpn-kl-int\\ca.crt"
cert "C:\\Program Files\\OpenVPN\\ovpn-kl-int\\server.crt"
key "C:\\Program Files\\OpenVPN\\ovpn-kl-int\\server.key"
dh "C:\\Program Files\\OpenVPN\\ovpn-kl-int\\dh.pem"
server 10.8.0.0 255.255.255.0
keepalive 10 120
cipher AES-256-GCM
persist-key
persist-tun
verb 3
explicit-exit-notify 1
push "route 192.168.100.0 255.255.255.0"
client-to-client

Client:

client
port 1194
proto udp4
dev tun
remote 88.99.1.1
keepalive 10 120
--remote-cert-tls server
cipher AES-256-GCM
persist-key
persist-tun
verb 5
explicit-exit-notify 1
pull

---cert entries following ---

What am I missing?

Thanks in advance.