UDP

Most internet traffic travels over one of two transport protocols: TCP or UDP. TCP first sets up a connection, keeps packets in order and resends the ones that get lost. UDP does none of this: it simply sends packets and does not wait for confirmation.

That makes UDP faster with lower latency, but some packets may never arrive. For many tasks this is fine: it is better to skip one video frame or a fraction of a second of audio than to pause a conversation and wait for a resend. UDP is chosen where quick reaction matters more than perfect accuracy.

UDP is used by:

• voice and video calls in messengers;
• online games, where every millisecond counts;
• live video and real-time streaming protocols;
• QUIC and HTTP/3, a newer version of the web supported by modern browsers;
• most DNS queries.

HTTP proxies never carry UDP: they work only on top of TCP. The SOCKS5 protocol has a separate UDP ASSOCIATE command for relaying UDP, but not every service supports it. Prokso proxies do not carry UDP - not on port 823 (HTTP), not on port 824 (SOCKS5) and not on the sticky IP ports.

In practice this means that messenger calls and online games will not work through Prokso proxies. Regular websites open without trouble: if a browser cannot connect over QUIC, it automatically falls back to HTTP/2 or HTTP/1.1 over TCP. You do not need to configure anything.

It is worth understanding that UDP is neither worse nor more advanced than TCP. It is simply a different approach: TCP cares about reliable delivery, and UDP cares about speed. Modern protocols such as QUIC add their own checks and resends on top of UDP, but do it more flexibly. For you the difference is simple: everything that runs over TCP goes through Prokso proxies, and UDP traffic does not. If a program can only work over UDP, a proxy is not suitable for it.

A separate case is WebRTC in the browser. This calling technology may try to send UDP directly, around the proxy, and then a site can see your real IP. The article on WebRTC leaks explains this in detail. Working with websites, scraping and ad verification usually do not need UDP at all, so the lack of UDP support does not affect these tasks.