Even in the logs, I can see that the server is pushing its own address as the gateway, yet pfSense does not use it as the gateway IP:

Dec 21 02:45:36 openvpn 67745 PUSH: Received control message: 'PUSH_REPLY,route-gateway 172.27.120.1,topology subnet,ping 10,ping-restart 120,ifconfig 172.27.120.2 255.255.255.0,peer-id 0,cipher AES-256-GCM'

I had this same issue and what worked for me is creating a floating rule on the downstream PfSense to allow WAN to LAN connections. YMMW.

Merci @ccnet pour votre retour.

Alors depuis mon espace OVH je vois bien une passerelle mais sur mon VPS, il n'y a aucune passerelle de configurer...

2001:41d0:0305:2100:0000:0000:0000:0001

Effectivement le but de ma démarche et d'obtenir une passerelle afin d'interconnecté mon VPS avec un réseau exterieur.

@grimm-spector Exactly, it will work just fine :)