Is the VPN Gateway capable of acting as an initiator or responder for S2S connections? If so where/how is this configured?
Azure VPN Gateways can be either or. By default its a responder. There’s no where to configure this as MFST takes care of handling based on the gateway config on the receiving end. (if your VPN device is a Initiator, MFST will be a responder and vice versa)
Azure VPN Gateway: About VPN devices for connections | Microsoft Docs