Because a TCP connection is not used, L2TP uses message sequencing to ensure delivery of L2TP messages. Within the L2TP control message, the Next-Received field (similar to the TCP Acknowledgment field) and the Next-Sent field (similar to the TCP Sequence Number field) are used to maintain the sequence of control messages. Out-of-sequence packets are dropped. The Next-Sent and Next-Received fields can also be used for sequenced delivery and flow control for tunneled data.
A lot of people avoid using VPN providers based out of the United States on the premise that US law would compel those providers to log all VPN activity. Counterintuitively, there are no such data logging requirements for US-based VPN providers. They might be compelled under another set of laws to turn over data if they have any to turn over, but there is no requirement they even keep the data in the first place.
That attitude to the safety and privacy of personal data creates an enormous online security risk. Public Wi-Fi networks, which are ubiquitous and convenient, are unfortunately also highly convenient for attackers looking to compromise your personal information. How do you know, for example, that "starbucks_wifi_real" is actually the Wi-Fi network for the coffee shop? Anyone could have created that network, and they may have done so in order to lure victims into disclosing personal information over it. In fact, a popular security researcher prank is to create a network with the same name as a free, popular service and see how many devices will automatically connect because it appears safe.
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