Solução encontrada: no servidor deve adicionar
cliente-para-cliente e outras coisas
para o cliente do Windows (como de costume ..)
então server.conf é
port 1194
proto udp
dev tun
ca ca.crt
cert server.crt
key server.key # This file should be kept secret
dh dh2048.pem
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
keepalive 10 120
tls-auth ta.key 0 # This file is secret
cipher AES-256-CBC
user nobody
group nobody
persist-key
persist-tun
status openvpn-status.log
verb 3
explicit-exit-notify 1
client-to-client
topology "subnet"
push "topology subnet"
push "route 10.8.0.0 255.255.255.0"