How to improve your network settings (the simple way)

If you feel that you sometimes just can't hit or dead-stop moving objects (like a jumping hunter or tank rocks) in Left 4 Dead 2's online games even though you try your best, then this guide could be very useful to you. I will explain how to adjust your network settings, which is crucial to making timing and shooting easier in Left 4 Dead 2.

The default settings are meant to compensate for unstable internet connections, but they are outdated for today's standards because internet connections have improved a lot since the game was released back in 2009. So if you think you have a decent computer and connection, you should adjust these settings to get the most out of them.

NOTE: If you don't have a decent computer and connection, changing these settings may cause some trouble while playing. If you find that you're not satisfied with the changes, you can undo everything by simply deleting the "autoexec"-file mentioned in this guide.

I will not explain the complex background of this guide's content. If you want to understand it and really know what you're doing, you can read through the following sources:

• L4DNation Lerp Article[www.l4dnation.com]
  
• Source Multiplayer Networking
  
• Optimising Your Configurations and How To autoexec
  
• Console commands and .cfg files, a basic guide
  

What is interpolation?

When you play online, your client-side game state (for example player positions, gunfire etc.) depends on something called "interpolation". To keep it simple, Interpolation is a delay and the default value is 100ms. When your computer receives updates from the server, it will use the last few received updates that came in in these last 100ms and combine them to calculate your game state.

This means that with interpolation your game's state is constantly behind the server's state, which has advantages and disadvantages. It makes your gameplay experience smoother, but your reaction is hindered since vision and your actions are basically delayed.

Example 1: If a hunter jumps towards you, on the server it may already have reached you, but on your computer the hunter model is delayed and will reach you 100 ms later, so your reaction and timing is hindered.

Example 2: You are shooting a jumping hunter in the distance. Due to the delay, The hunter model is virtually a few meters behind the actual server-side hitbox. So if you aim for the model, you will have a hard time hitting him.

Therefore if you want your view to be more accurate and closer to the server's state, you need to decrease the interpolation value.

One easy way to change it is to create an "autoexec" config file which enables you to choose your desired interpolation value using the function keys on your keyboard. Furthermore, it will tweak some other useful settings that you don't need to know about.

Follow these 7 steps to create the autoexec file and to adjust your interpolation:

7 steps

1. Find your left 4 dead 2 config folder. The default path is:
"Program Files (x86)\Steam\steamapps\common\Left 4 Dead 2\left4dead2\cfg"



















2. Rename/change the filename "autoexec.360.cfg" to "autoexec.cfg". Pay attention to every single letter.

3. Open the renamed file with your standard text editor.


















4. Delete all of the text inside the file.

5. Copy and paste the following:

bind "TAB" "+sb";
alias "+sb" "+showscores; net_graph 1";
alias "-sb" "-showscores; net_graph 0";

bind "F5" "cl_interp 0.0"
bind "F6" "cl_interp 0.016"
bind "F7" "cl_interp 0.033"
bind "F8" "cl_interp 0.066"
bind "F9" "cl_interp 0.1"

rate 30000
cl_cmdrate 100
cl_updaterate 100
cl_interp_ratio -1
cl_lagcompensation 1
cl_interp 0.067

6. Now while in the game you can conveniently change your interpolation values by pressing the according function keys:

F5 = 0 ms (nearly)
F6 = 16.7 ms
F7 = 33.3 ms
F8 = 66.7 ms
F9 = 100 ms

NOTE: Every time you start Left 4 Dead 2 the value will be reset to 66.7 ms, so you need to readjust it some time after launching the game. Better change it while playing a game.

7. During a game press the TAB key to check what your new interpolation value is. It is shown on the bottom right next to the word "lerp."

Which interpolation value should you choose?

Low interpolation values make your view more accurate, but less smooth. Moving objects may 'teleport around' or may not be easy to follow, depending on your connection and the server tickrate.

High interpolation values make your view less accurate, but smoother. Hitboxes will be ahead of their models.

So try out different interpolation values, try to find out the differences they make in the game and stick with a value that you feel comfortable with. You should choose a value which is low enough to let you aim well and high enough to not let you be confused by stuttery movement.

Note that in singleplayer there is no lag, so only low interpolation values make sense here.
And if you play on Valve's official servers or local games, your interpolation value won't be exactly zero because the low tickrate doesn't allow that, which can't be changed unfortunately.

If you have questions, feel free to post a comment or read the aforementioned sources.

I hope that this guide improves your playing experience and accuracy.

[most sane l4d2 player]

These commands literally increases your ping by 20+
To me that is basically sabotaging ourselves3

Solution w/0.067 interp and LOWER ping:
cl_interp 0
cl_interp_ratio 2
cl_updaterate 30
cl_cmdrate 30
rate 30000

[Niky]

@BottomScorer on offline with bots?

[BottomScorer]

My ping went up from 30 to 50 after these commands:

rate 30000
cl_cmdrate 100
cl_updaterate 100
cl_interp_ratio -1
cl_lagcompensation 1
cl_interp 0.067

[76561198268536306]

@crimson if you have this problem on this pc and the last one it could be another problem you need to delete a specific folder in steam > userdata but forgot the whole path, for all of what I said below search each of them on internet like "how to reset l4d2" we're in 2022 most answers are on internet

[Maoy]

@Crimson
I'm afraid I don't have any concrete advice about that, sorry. I'm not familiar with local servers and I don't know any more which commands are permanent and which need to be reset. Overall I think your issue isn't related to my networking guide.
I can only recommend that you do some research about the source engine's networking and performance, for example here: https://developer.valvesoftware.com/wiki/Source_Multiplayer_Networking

[Manhattan Cafe]

For the record everything started yesterday randomly with this brand new pc, but i had this problem with my older computer which had an i3 and same gpu, it lagged even in a solo campaign with bots, and wasn't fps lag, that's why i think some update fucked the game up for me.

Always played local server, or most of the time and didn't touched any network related command.

[Manhattan Cafe]

Any guide on how to reset everything?

Thing is, it shouldn't be a performance issue cause i have an i7 with a 750ti gpu, so it should run with no problems even with everything maxed out.
Fps never go down and it's always when a event starts/horde spawns, i think it's more like warping rather than lag, if that makes sense, everything teleports and responds delayed.

I barely have any addons installed but i tested it without any mods anyway, and everything happened randomly after i noticed that they updated and changed some things regarding local servers, and servers in general i think.

[76561198268536306]

@crimson I think that this is a problem related to "rate ??" on your local server you should have less than 5 ping, find a way to reset all the settings including network ones then launch a local server, if you still have the problem check if you have any addons installed, unsubscribe to all and reinstall the game, after all of that if you still have the problem, which I doubt, there's a problem with your pc or your pc doesn't have enough performance, to check that go on a website site like "RateMyPc" and search for left 4 dead 2

[Maoy]

@Crimson
What you're describing sounds like a performance issue and can get worse if you apply the changes in this guide. It can't fix your connection's latency/ping or performance.

[Manhattan Cafe]

So this can fix having lag on your Own local server? Whenever i get to a part with huge hordes or they start spawning a lot, it's so fucking insufferable.

Own fucking local server and ping goes up to 240 the hell happened to this game.