"My proxy isn't working" — the TCP, UDP and connection-type checklist

"My proxy is not working" can describe several different failures: authentication, endpoint reachability, protocol mismatch, DNS, an unsupported UDP path, poor radio performance or one destination rejecting a request. Test those layers separately so one successful IP check is not mistaken for proof that every application works.

The one distinction: TCP vs UDP

Internet applications commonly use TCP or UDP. TCP provides an ordered, retransmitted byte stream. UDP sends datagrams without TCP's delivery and ordering guarantees, and protocols such as QUIC build their own reliability where needed. Web traffic can use TCP through HTTP/1.1 or HTTP/2, or UDP through HTTP/3.

Trump Proxies' HTTP and SOCKS5 endpoints carry TCP. Although the SOCKS5 specification includes a UDP-associate command, support is product-specific and is not included on these proxy endpoints. Use a full VPN plan when the workload requires whole-device UDP routing.

Why our proxies speak HTTP and SOCKS5

When you buy a mobile proxy from us, you get an ip:port with a username and password, and you connect to it as either an HTTP proxy or a SOCKS5 proxy. Both ride TCP. The difference is reach:

• HTTP(S) proxy — purpose-built for proxy-aware web clients. HTTPS is normally carried through an encrypted CONNECT tunnel.
• SOCKS5 proxy — lower-level and more general: it forwards TCP connections beyond web requests, so it works with a wider range of compatible software. It uses the same assigned service endpoint and carrier-controlled exit path.

Use whichever mode your software supports. In clients that recognize it, socks5h:// asks the proxy side to resolve hostnames. Client behavior varies, so verify the observed DNS path instead of assuming the scheme alone prevents every local lookup.

When a UDP setting causes an application failure

Some clients expose a "UDP Relay" or "UDP forwarding" option. If that option expects SOCKS5 UDP support from a TCP-only endpoint, UDP flows can fail even while ordinary TCP requests work. Whether the application falls back depends on the application and protocol.

Many web services can fall back from HTTP/3 over QUIC to HTTP/2 or HTTP/1.1 over TCP, but fallback behavior is application-specific. Voice, video, games and some native apps may depend more heavily on UDP. Test the real application rather than assuming either transport is optional.

When you actually need UDP: the VPN tier

Some workloads need a whole-device tunnel with TCP and UDP support: full-device setups, apps that do not fall back or clients without per-app proxy settings. That is why we offer mobile proxies over VPN through WireGuard or OpenVPN. Verify the exit, DNS and split-tunnel settings on the actual device before assuming every application uses the tunnel.

• WireGuard — a lean UDP-based protocol that often has low overhead and supports whole-device UDP routing.
• OpenVPN — a mature option with broad client support and UDP or TCP transport; TCP-443 may work where the access network blocks UDP.

The product boundary is deliberate: HTTP/SOCKS5 endpoints carry proxy-aware TCP traffic, while the VPN product routes the device and supports UDP. If the workload depends on UDP, choose the VPN line. For a deeper comparison, see WireGuard vs OpenVPN for a mobile line.

The 60-second "is it actually broken?" checklist

Before assigning a cause, run these in order:

1. 01Check authentication and the exit. An IP-check response proves that one TCP request reached that checker through the endpoint; it does not validate every app.
2. 02Check transport requirements. Turn unsupported UDP relay off for a proxy test, or use the VPN plan when UDP is required.
3. 03Confirm HTTP vs SOCKS5. Use the mode your software expects; if DNS matters, prefer socks5h:// so lookups go through the line.
4. 04Avoid requested rotation mid-session. It can change the network input during a stateful task, while natural carrier changes remain possible.
5. 05Compare scope. If general connectivity works but one destination fails, record the exact app, account, time, error and exit IP for investigation.