# Support – UDP TCP Sender & Receiver

Welcome to the support page for **UDP TCP Sender & Receiver**. Here you can find answers to common questions, learn how to use the app, and get in touch with us for help or feedback.

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## Frequently Asked Questions

### General

**Q: What is UDP TCP Sender & Receiver?**  

A: UDP TCP Sender & Receiver is a network testing tool for developers, IT professionals, and hobbyists. It lets you send and receive UDP packets, connect as a TCP client or run a TCP server, and ping hosts to check connectivity—all from your phone or tablet.

**Q: What platforms does the app support?**  

A: The app runs on iOS and Android. Some features may differ slightly between platforms.

### UDP

**Q: How do I receive UDP packets?**  

A: Open the **UDP** tab, enter a **Local Port** (e.g. 5000), and tap **Start Listening**. Your device will listen for incoming UDP packets on that port. Share your Local IP and port with whoever will send data to you.

**Q: How do I send UDP packets?**  

A: In the **UDP** tab, enter the **Remote IP** and **Remote Port** of the target device, type your message, and tap **Send**. You can switch between **UTF-8** (text) and **Hex** mode for binary data.

**Q: Why am I not receiving UDP packets?**  

A: Check that: (1) the receiver is listening on the correct port, (2) both devices are on the same network (or the sender can reach your public IP if applicable), (3) no firewall is blocking the port, and (4) the sender is using the correct IP and port.

**Q: What is Hex mode?**  

A: Hex mode lets you send raw bytes as hexadecimal (e.g. `48 65 6C 6C 6F` for "Hello"). Use it for binary protocols or non-text data.

### TCP Client

**Q: How do I connect to a TCP server?**  

A: Open the **TCP Client** tab, enter the server's **Remote IP** and **Remote Port**, then tap **Connect**. Once connected, you can send messages in UTF-8 or Hex mode.

**Q: Why does the connection fail?**  

A: Common causes: wrong IP or port, server not running, firewall blocking the port, or the server not reachable from your network. Verify the server is listening and that you can reach it (e.g. via ping).

**Q: Can I connect to servers on the internet?**  

A: Yes. As long as the server is reachable from your network and the port is open, you can connect to any public TCP server.

### TCP Server

**Q: How do I start a TCP server?**  

A: Open the **TCP Server** tab, enter a **Local Port** (e.g. 8080), and tap **Start Server**. The app shows your **Local IP**—clients should connect to this IP and port.

**Q: How do clients connect to my server?**  

A: Clients need your device's IP address and the port you chose. On the same Wi‑Fi, use the Local IP shown in the app. From another network, you'd need port forwarding on your router (advanced).

**Q: What does "Broadcast Message" do?**  

A: It sends the same message to all connected clients at once.

**Q: Why does my Local IP show "Loading..." or "N/A"?**  

A: The app is detecting your network interface. If it stays that way, ensure Wi‑Fi or cellular is enabled and you have an active connection.

### Ping

**Q: How do I ping a host?**  

A: Open the **Ping** tab, enter a hostname (e.g. `google.com`) or IP (e.g. `8.8.8.8`), set the **Count** (1–100), and tap **Ping**.

**Q: Why does ping fail?**  

A: The host might be down, unreachable, or blocking ICMP. Some networks block ping. Try a different host (e.g. `8.8.8.8`) to test your connection.

**Q: What does "Count" mean?**  

A: It's the number of ping packets to send. Default is 4.

### Troubleshooting

**Q: The app shows an error when I try to send or connect.**  

A: Double-check IP addresses (valid IPv4), ports (0–65535), and that the other side is running and reachable. Restart the app and try again.

**Q: Can I use the app in the background?**  

A: Network operations may be limited when the app is in the background. Keep the app in the foreground for reliable UDP listening and TCP connections.

**Q: How do I switch between light and dark mode?**  

A: Tap the sun/moon icon in the top-right of the app bar.

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## Need Help?

You can reach us by email at shrimpstudio435@gmail.com or by submitting the feedback form below. Please describe your question or issue in detail so we can assist you quickly. We typically respond within 24–48 hours.

**Email:** shrimpstudio435@gmail.com 

**Phone:** +852 6464 3622

**Feedback Form:** Use the form below to report bugs, suggest features, or share your opinion. We read every submission.

Thank you for using UDP TCP Sender & Receiver.