Thanks for posting your question in the Microsoft Q&A forum.
The throughput of a VPN Gateway, such as VpnGw1, is not the same as the bandwidth of your internet connection. The throughput of the VPN Gateway refers to the maximum aggregate data transfer rate that the gateway can handle. This includes both inbound and outbound traffic.
In your case, if your internet bandwidth is 100Mbps and the VpnGw1 has an aggregate throughput of 650Mbps, the VpnGw1 should be sufficient for your needs in terms of throughput. This means that the VPN Gateway can handle traffic up to 650Mbps, which is more than your internet connection's bandwidth of 100Mbps.
It's important to note that while the VpnGw1 can handle traffic up to 650Mbps, other factors such as latency, network congestion, and the performance of the endpoints can also affect the overall performance of your VPN connection.
** Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful **