Fixing Packet Burst Issue on Modern Warfare III

Packet burst is causing MW3 players no end of trouble, and we’re been having issues since the game released. Harriet was having a problem where pretty much every match in Modern Warfare III, she was getting packet loss and rubber banding – it made the game almost unplayable… until we fixed it!

Here’s a bit of background.

We have three PCs all running Modern Warfare III (MWIII) in our house.

UserCPUGPUOther Info
Me (Sean)Zen 3 – 5900XNvidia RTX3070Windows 10, 32GB of RAM, and game installed on SSD
HarrietZen 3 – 5900XAMD 6700XTWindows 11, 32GB of RAM, and game installed on SSD
ZacZen 3 – 5600XAMD 5700XTWindows 10, 32GB of RAM, and game installed on SSD

All of the PCs are connected via Gigabit Ethernet to our internet router and our internet connection is a very solid 1000Mbps connection. We also have the exceptionally good fortune of living less than five miles as the crow flies from the primary data centre that houses the Call of Duty servers in Australia, so our average latency in game is sub 10ms (usually 8-9ms).

Here’s the problem:

Zac and I have basically, zero problems with our connection to the game, but Harriet has constant packet loss and horrible rubber banding issues in MWIII.

The constant cries that you see on Reddit and Twitter of, “The servers suck” may have an element of truth to it, but if that were the case, why would only Harriet be having this problem?

So I did some thinking and investigations, and as of today, those issues that she was experiencing are gone.

Here are the things that I changed.

Updated Network Drivers with OEM Drivers

Normally, Windows Update just takes care of your basic drivers for your network card or things like Bluetooth and it’s generally best to leave it like that.

However, in a situation like this, it’s often just better to replace the drivers with something from the manufacturer of your motherboard just to eliminate that.

She’s running an MSI motherboard, so I went to the MSI site, downloaded the most recent Realtek 1GBe LAN drivers, and ran the package.

To my surprise, the MSI driver pack installed a new Family Controller and replaced the Microsoft Windows 11 version. The Windows Hardware Quality Labs (WHQL) tested drivers are often just generic by the component manufacturer so they will “work” out of the box, but they may not be properly optimized for your specific motherboard.

Again, I’m not certain whether this had any impact, but it was the first thing I did.

Added Windows Firewall Rules

MWIII uses specific, well-known TCP/UDP ports to communicate with servers and if your Windows Firewall is blocking are filtering those, that’s a problem that will look like dropped packets.

You’ll also have issues with your “NAT Type” not being “open” which is more likely to cause matchmaking issues, but that’s a separate problem. NAT (Network Address Translation) is a bigger problem and outside the scope of this piece – if your ISP uses CG-NAT (Carrier Grade NAT) then you might have issues. Our ISP just turns it off when you request it, so it’s never a problem for us.

Ok, so back to the firewall rules.

I added a couple of Inbound Rules for UDP and TCP ports:

ProtocolPort Numbers
UDP3074, 4380, 27000-27036
TCP3074, 3075, 27015-27030, 27036-27037

The game will try to open those ports in Windows Defender itself when you first run it, but it’s worth just adding them into your Inbound Rules again.

Name them descriptively, I called mine, “SK-MWIII-UDP” or “SK-MWIII-TCP” so that I can always disable them or modify them quickly.

Checking the Ethernet Cable

We’re using high-end Cat6e cables, so I doubted that there was anything wrong with the cables, so I just did a quick “unplug/replug” on both ends of the cable just to make sure.

The reality is, if your Ethernet cable is crimped or splayed and not making solid connections, you’ll be able to test for that pretty easily because it won’t be game-specific. You can just go to a testing tool, add enough time and packets, and eventually, if you have a cable or physical port issue, it will appear.

But just for the sake of completeness, I did this.

Changed the VRAM Scale Target

Ok, straight up, I saw this on Reddit and couldn’t figure it out – why would changing the VRAM scaling target have any impact?

But several people, and I do mean, several, said that making this change INSTANTLY remedied their problem.

I dropped Harriet’s VRAM scaling target from 90% to 70%.

A screenshot of the settings for Modern Warfare III game with a focus on fixing the packet burst issue.
Sean’s settings with his Nvidia RTX3070 – thus the DLSS

In game terms, it shouldn’t make any difference, the 6700XT is a 16GB VRAM card, so 70% scaling will be fine. On the 8GB cards that Zac and I run, that could be a problem requiring us to lower visuals, but we’re not having the problem.

It’s Now Fixed… No More MW3 Packet Loss and Rubber Banding

The Packet Burst and Rubber Banding that plagued her gaming experience was gone… not reduced, eliminated entirely.

If I had to guess, I’d say that it’s either the replacement of the LAN drivers or, inexplicably the VRAM Scaling that resolved the problem.

The LAN card drivers would make the most sense from a “simple answer is the most likely” but again, those NIC drivers weren’t causing problems in anything else – games, productivity, general use… nothing. To suggest that there was something wrong with the LAN card drivers that were specific to MWIII and were repaired by installing almost year-old OEM drivers seems a stretch.

This leads me to the VRAM Scaling Target.

I could test it, but I doubt Harriet is keen to have me adjust this now that it’s finally working for her and she’s having a good experience, so this will stay firmly in the “working hypothesis” camp for now.

Either way, it’s the easiest thing to test if you’re having this problem – go into the game, change your VRAM Scaling Target back to 70, and see what happens.

I hope this helps someone and if you have an explanation on why that might work, drop a comment below.

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Sean Kaye
I've been playing video games since the early 1980's on a Commodore Vic 20 and then eventually a C64. I graduated up through the Amiga and into PC Gaming in the early 1990s. I've owned almost every console platform imaginable ranging from the Atari 2600, Intellivision, and Sega Genesis through to multiple Xbox, Playstation, and Nintendo systems along the way. I'm a fan of Call of Duty, Football Manager, and just about any kind of management/tycoon kind of game you can think of. My hobby extends out to the tech side of things - I like playing with PC gear and streaming tech in my spare time.

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