---
title: Why Does Access Server Use UDP and TCP?
canonical: https://openvpn.net/as-docs/faq-udp-and-tcp/
product: Access Server Docs
---

# Why Does Access Server Use UDP and TCP?

**Question:** Why does OpenVPN use UDP and TCP?

**Answer:**

OpenVPN uses UDP for optimal performance but supports TCP for compatibility with restrictive networks. TCP 443 is used to mimic HTTPS traffic, often allowed through firewalls.

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