This guide goes well with these (in order):

  1. Understand Your Public IP
  2. TCP vs UDP
  3. How to Set Up Port Forwarding

TCP vs UDP (And Why Games Use UDP)

When setting up port forwarding, you'll often see:
  • TCP
  • UDP
  • Both
If you don't know the difference, here's the fast exaplanation.

TCP: Reliable but Slower

TCP stands for Transmission Control Protocol. It is:
  • Connection-based
  • Reliable
  • Ordered
  • Error-checked
Before sending data, TCP does a handshake. In other words: 

- "Are you there?"
* "Yes."
- "Okay, sending data."
If a packet is lost:
  • It gets re-sent
  • Packets arrive in order; 1-2-3-4-5
This makes TCP perfect for:
  • Websites (HTTP/HTTPS)
  • File downloads
  • Email
  • Remote desktop
Accuracy matters more than speed.

UDP: Fast but Unreliable

UDP stands for User Datagram Protocol. It is:
  • Connectionless
  • No handshake
  • No guaranteed delivery
  • No automatic re-sending
UDP just sends: "Here. Take it." If a packet is lost? - It's gone - No retry.

So Why Do Games Use UDP?

Because in games:
  • Speed matters more than perfection
  • Late data is worse than lost data
Imagine this situation:
  • Your character moves left
  • The packet gets delayed
  • TCP resends it
  • It arrives 300ms late
You character would "teleport" to the left after the delay - That would feel terrible. With UDP:
  • If one movement packet is lost
  • The next one updates your position instantly
No waiting, no backlog, just current state.

Real-Time Traffic Needs Low Latency

Games send constant updates like:
  • Player position
  • Rotation
  • Shooting events
  • Physics updates
These happen many times per second. Waiting for confirmation would:
  • Increase latency
  • Increase jitter
  • Feel laggy
UDP keeps gameplay responsive.

Does That Mean UDP Is “Worse”?

No. It's just designed differently. For a different purpose. TCP is great for things that need reliability. UDP is great for things that need speed.
Feature TCP UDP
Reliable delivery Yes No
Ordered packets Yes No
Low latency Moderate Very low
Used by games Sometimes Very often

Important: Some Games Use Both

Many modern games use:
  • UDP for gameplay traffic
  • TCP for login, chat, downloads, updates
If you are forwarding ports and unsure which to forward:
  • Check the game documentation
  • Or forward both (if required)

Speedy Summary

  • TCP = Reliable, ordered, slower
  • UDP = Fast, minimal overhead, no guarantees
  • Games prefer low latency over perfect delivery
If you're hosting a game server, it will usually require UDP ports to be forwarded.