Setting up a roblox custom connection filter script is one of those things that sounds way more complicated than it actually is until you're staring at a blank script editor in Studio. If you've ever played a game where players are teleporting all over the place or the server feels like it's running on a potato, you know how frustrating bad connections can be. As a developer, you want your game to run smoothly for everyone, but sometimes a few players with high latency can ruin the experience for the whole lobby. That's where a custom filter comes into play.
Basically, you're looking to create a gatekeeper for your game. You want to check who's coming in, see if their internet can handle the heat, and decide whether to let them stay or gently show them the door. It's not about being mean; it's about server health.
Why Bother with a Custom Filter?
Roblox does a decent job of handling networking on its own, but it's a "one size fits all" solution. When you're building something specific—like a fast-paced competitive shooter or a complex physics-based hobby—the default settings might not cut it. If someone joins with a 900ms ping, they aren't just lagging for themselves; they're often causing the server to struggle as it tries to reconcile their position with everyone else's.
By using a roblox custom connection filter script, you're taking control. You can set specific thresholds for what you consider an "acceptable" connection. Maybe for a hangout game, you don't care if someone has a high ping. But if you're making a game that requires frame-perfect timing, you might want to be a bit stricter.
How the Logic Usually Works
The core of a connection filter is usually a script sitting in ServerScriptService. It waits for a player to join and then starts a "probing" phase. You can't just check a player's ping the microsecond they join because the initial loading process usually causes a massive spike that isn't representative of their actual connection.
Usually, the script waits a few seconds after the PlayerAdded event fires. Then, it uses a remote event to ping the client and wait for a response. By measuring the time it takes for that round trip, you get a solid idea of their latency. If the number is too high, the script triggers a kick message.
Setting Your Thresholds
This is the part where most people get stuck. What's a "bad" connection? If you set the limit at 100ms, you're going to kick half of the players on the platform. If you set it at 1000ms, the script isn't really doing anything.
A good middle ground is usually around 300ms to 500ms for casual games. For anything competitive, you might want to look at 200ms. Just remember that people's internet fluctuates. A good roblox custom connection filter script shouldn't just kick someone the first time they lag. It's better to sample the ping over five or ten seconds and take an average.
Building the Script Safely
When you're writing the code, you have to be careful not to create more lag than you're trying to prevent. If you have sixty players in a server and you're pinging all of them every single second, that's a lot of unnecessary traffic.
Instead, focus on the "onboarding" phase. Once a player is in and their connection is stable, you probably don't need to check them constantly unless the server starts acting up. You can use a while loop with a long wait time or just run the check once when they first join the game.
Also, make sure your kick messages are helpful. Instead of just saying "Disconnected," try something like, "Your connection is a bit too unstable for this server right now. Try checking your Wi-Fi!" It makes the experience a lot less jarring for the player.
Dealing with False Positives
There's nothing worse than getting kicked from a game because your computer stuttered for half a second. To avoid this, your roblox custom connection filter script should have a "grace period."
Give the player a chance to load the assets. Sometimes, a player's ping will jump to 2000ms while they're downloading all the high-res textures and sounds you've packed into your map. If your script kicks them during that window, they'll never actually get to play. A thirty-second window at the start of the session is usually enough for things to settle down.
Advanced Filtering Options
If you want to get fancy, you can go beyond just checking for ping. Some developers use custom filters to check for other things, like whether a player is using a VPN or if they're coming from a specific region that's currently having server issues.
While Roblox doesn't give you a direct "Is this a VPN?" button, you can look at certain headers or use external APIs (with HttpService) to get more info about the connection. This is getting into the weeds a bit, but for big games, it's a common practice to keep things secure and optimized.
Regional Filtering
Sometimes, the issue isn't the player's internet—it's the distance to the server. If you're running a game with servers in the US and someone joins from halfway across the world, they're going to have high latency no matter how fast their fiber connection is.
You can use the LocalizationService to see where a player is located and, if your script is sophisticated enough, you can suggest they join a server closer to their home. It's a lot more work to set up, but it makes your roblox custom connection filter script feel like a professional tool rather than just a "kick bot."
Testing Your Script
Testing connection filters is notoriously annoying because, well, you probably have a good connection to your own Studio session. To really see if it works, you'll need to simulate lag.
There are plenty of third-party tools that let you throttle your own internet speed. By setting your outgoing speed to something miserable, you can join your game and see if your script catches you. If it kicks you immediately during the loading screen, you know your grace period is too short. If it never kicks you even when you're lagging out of your mind, your threshold is too high.
Keeping It Optimized
At the end of the day, your roblox custom connection filter script should be invisible. The players who have good connections should never even know it exists. It should sit quietly in the background, doing its job without eating up CPU cycles.
Keep your code clean, use variables to easily tweak your thresholds without digging through lines of logic, and always keep the player's experience in mind. A smooth game is a successful game, and a little bit of gatekeeping on the networking side goes a long way toward making that happen.
If you're just starting out, don't overthink it. Start with a simple ping check, see how it affects your player retention, and adjust from there. You'll find that even a basic filter can drastically improve the "feel" of your game's movement and combat. It's one of those small dev tricks that makes a massive difference in the long run.