Unreal Engine 4.9.1 Editor TCP and UDP Problem?

I created a ThirdPerson Template project, and I noticed on my cell phone wireless icon the download arrow stayed a steady solid.

I disconnected my computers ethernet cable that had Unreal Engine Editor opened and the data traffic stopped.

I plugged in the cable and the data traffic started again.

I closed Unreal Engine Editor and the data traffic stopped.

Re-opened Unreal Engine and the data traffic started again.

I checked my Firewall logs and saw each device on my network connected to my modem/router shows these when Unreal Engine Editor is opened, it doesn’t do this with the launcher.

UDP Generic Discards

TCP Downstream direction: malformed tcp-header

UDP Downstream direction: malformed udp-header

TCP Downstream direction

UDP Flood-limit

It seems as if this might be impacting all the devices connected on my network, what should I do to further troubleshoot and solve this?

Hi KnightTechDev,

Can I get a breakdown of the hardware you’re using? I’ll need your dxdiag for your PC, your phone model number and OS version, as well as your Router/Modem model number(s). Any additional info will be helpful.

-Matt W.

DXDiag is attached, Modem/Router is Arris NVG589 for ATT UVerse 18MBps.

The machine running the UE4 editor:

Case: Chieftech Scorpio Silver TX1/T1 Full Tower

Motherboard: Gigabyte F2A85XM-D3H Socket FM2

Processor: AMD A8-6600K APU with Radeon™ HD Graphics (4 CPUs), ~3.9GHz

Operating System: Windows 10 Pro 64-bit (10.0, Build 10240)

System Manufacturer: Gigabyte Technology Co., Ltd.

BIOS: BIOS Date: 04/08/2013 Ver: 04.06.05

Memory: Ballistix LED 8192MB RAM DDR4 (AMD/XMP Profile)

Page file: 2171MB used, 5967MB available

DirectX Version: 11.2

Videocard: Gigabyte AMD Radeon HD 5770 GDDR5 1GB (Approx. Total Memory 4850MB)

ATI Driver Version: 15.8

Current Display Mode: 1920 x 1080p (32 bit) (60Hz)

Display: Philips Smart LED 46" FTV

Driver Model: WDDM 1.3

Driver Version: 15.201.1151.0

Driver Date: 08/21/2015

TV Sound: AMD HDMI Output (AMD High Definition Audio Device)

Built-in Sound: Realtek HD

Speakers: Creative Labs Inspire 4.1 EAX

Mouse and Keyboard: Logitech M215 and K360

It impacts all devices connected, like Samsung Galaxy Note 2 (SGH-I317) (Android 4.4.2 with SE Policy Enforced June 24 2015), iPad 2 with IOS 8 (haven’t downloaded iOS 9 yet), Apple iTouch 2, Toshiba Thrive, Toshiba Satellite, Inspiron 530 (About identicle configuration as the UE4 editor one only with an NVIDIA Galaxy GT220 video card and Intel Core2 Quad Core processor 8GB RAM, Windows 10 Pro, Etc.), Etc…

I have Unreal Tournament Port enabled on the modem/router, I’m puzzled as to the data coming out from the editor and why it does it simply when the editor is opened and project loaded but not playing.

It doesn’t seem to matter the hardware, it’s whenever I open the editor it seems to send out a bunch of data that all devices ethernet and wireless adapters download the entire time the editor remains open.

link text

The wireless service common setup is for Wireless N via 300MBps or 600MBps optimal traffic though the older devices run 150MBps G down to 54MBps G for lower signals, and the ethernet adapters are running 1GBps Full.

I have noticed 4MBps to 6MBps drops and sometimes interruptions in normal internet traffic on these devices with the editor opened and 3 complete TV lockups during NetTV usage requiring manual unplug and replug and power up of TV, which I’m not certain is related, but if the packets are flooding the adapters through the raw traffic it’s possible.

The machine running the UE4 editor is Windows 10 Pro 64 bit fresh install on OCZ Vertex 4 128GB with minimal tools installed and Hitachi and Samsung with Barracuda Green for Storage.

Hey KnightTechDev,

We had a user a while back with a similar issue. Would you mind trying the accepted answer on this thread?

-Matt W.

Ok, I checked the post and it’s very helpful it is isolated to the UDP Messaging Plugin, after making the change in the UDP plugin file that stopped the traffic from being sent out from the editor and bouncing like discovery service to the other devices on the network and the bandwidth flooding stopped and all devices on the network are fully responsive now with normal speed test results.

I came across a few search results online about some older Unreal Engine network security issues and one related to the Google UDP Cryptographic Analysis Vulnerability Scanning and Unreal Engine 3, and result saying people recommend "blocking all UDP traffic to any device that has port 7777 enabled via the router."

The problem is I am working on a multiplayer game for the long term and experimenting with some smaller multiplayer projects and so this will require the editor and services being enabled to work properly if I am correct, correct me if I’m wrong?

Atleast we know it is isolated to the UDP plugin and via the UDP traffic, even if I set the port forwarding to isolate the service, I would assume it would still cause problems for clients connecting remotely to local service end points and possibly cause lag over the network, I do not know what the effect would be outside the network on third party routers and networks, it may produce similar results on their end as well lowering network performance of the clients, that would impact multiplayer game performance as well possibly giving a jittery network experience, I hope not.

It seems like the person that had the issue with Linux and their TV is pretty spot on with what I experienced, and my TV totally froze and wasn’t responsive to anything so I literally had to pull the power plug and plug it back in to regain control of my TV as it wouldn’t even respond to remote control, it’s unnerving when unplugging the TV and the speakers pop, and you know the TV isn’t supposed to be unplugged that way when it has some requirements about not doing that for other things.

The TV was not connected to any cable service via coax, it was connected via ethernet to the modem/router for internet only service, and there’s nothing else on the line in between.

The effects on the TV end were first noticable when I was watching Youtube video’s on the TV and the video’s became choppy and I tried to switch video’s.

For now I’m leaving the TV unplugged network wise from the network (No Ethernet or Wireless) with the built-in NetTV features off, and so far no problems.

Is your PC connected to the Arris NVG589 via a cable or via WiFi?

If it is connected via WiFi, your router may be flooding the other wireless devices with multicast traffic from the Editor. Now, the Editor sends only very small amounts of data, so my guess is that the device is not handling multicast traffic correctly.

For testing purposes, can you try to connect your PC via an Ethernet cable to the router and disable WiFi on the PC?

Hey KnightTechDev,

We’re going to try and get an NVG589 router and reproduce this locally. I’m going to mark this as answered for now for tracking purposes though.

-Matt W.

I was able to get an NVG589 off Craigslist tonight - will try to repro it tomorrow.

I have entered UE-21897 in our system to track the progress.

Sorry for the delay We finally had some time to look into this. Unfortunately, we were not able to reproduce the problem so far. KnightTechDev, would you be able to investigate the problem with us? It could be that it is some interaction with other hardware you have connected. For example, it could be possible that the TV set reacts badly to the UDP multicast packets, and that the high network traffic is originating from there and not from the router.

Very sorry for taking so long to get back, I had to put on hold to recover from physical injury and dealt with family member passing away and my girlfriend being in hospital in another country and other issues.

I’ve checked it out more and it was passing from the editor through the messaging to all devices on the network and flooding them as thought, taking the advice as described to disable the messaging of the editor stopped that traffic from happening and the network becomes fully responsive again. It sends the traffic to all devices connected to the router which is why it’s affecting the other devices, disconnecting the TV from the network results in the TV never freezing and screen not locking up but the traffic still goes through the network to other devices, when I look at my devices internet icons it reflects steady and continuous inbound traffic and confirms the routers logs. For example, on wireless devices you will see the lower bar for the wireless icon showing and arrows indicating direction of data traffic movement. Blocking the editor’s internet access with a firewall also stops this traffic from happening.

If you look at TCPView it will also indicate this traffic as outbound traffic.

When I looked before at the traffic it was still being distributed over the network to all the other devices which means it’s not the TV doing it. I need to check the latest Unreal Engine versions and see if this is still happening. I also have some other brand routers can test. Netgear, Linksys, D-Link, etc.

I will certainly investigate this more as time permits, because it does impact network performance of all devices connected aside from locking my TV up, and I would like to develop multiplayer game(s) while maintaining network performance and if I publish a completed game on a third party server like Amazon would need to be sure the outward traffic from this happening would not increase service costs too much from a continuous stream or something I cannot see or diagnose on the third party server virtual host, if it does it on my local network then I can assume it might on third party host server. So it does validate further investigation.

Thank you for your patience, and sorry again for taking so long.

The Arris NVG589 was connected via Cat 6 Ethernet cable T568B directly to the PC.

During testing I tried multiple configurations of wired and wireless to try and isolate, both with multiple devices connected and then tested with minimal one computer and one other device. Tested with wireless access on and off. I used TCPView which also indicated the outgoing traffic. It was the UDP messaging plugin doing it.

Still does it.

Current stable release version of Unreal Engine 4.11.2 shows this so far:

The Epic Games Launcher sends out continuous UDP Packets, this video is showing some UDP traffic with TCPView:

The Unreal Engine Editor sends out continuous UDP Packets, this video is showing some UDP traffic with TCPView:

Epic Games Launcher:
Processor Usage: 0.1%
Memory Usage: 300.4MB
Disk Activity: 0MB
Network Usage: 0.1Mbps

Unreal Engine Editor:
Processor Usage: 0.7 - 2.0%
Memory Usage: 292.5MB
Disk Activity: 0.1MB
Network Usage: 0.1 - 1Mbps

Are the packets being sent out on the network for some form of continuous network discovery for the connectivity of clients in this manner because they are able to be passed freely along the entire network to each device?

Thanks for looking into this again! When you say “flooding”, what amount of packets are we talking about? The messaging packets are using multicast, so they are expected to be sent to all subscribed multicast endpoints. If you don’t have any other instances of the Engine open, all packets should be discarded by your router. Even if they are forwarded, there shouldn’t be more than a few per second.

This traffic is normal and expected. The Engine will send about one packet per second for network discovery, yes.

So, the volume of the traffic is clearly not the problem here. I think there may be two other issues interacting with each other:

  1. Your router is forwarding multicast packets to other network interfaces even though these are not subscribed to the mulitcast group (this seems to be a bug in the router)

  2. Your IPTV is somehow responding in a bad manner to multicast packets received on port 6666 (this may be a bug in the multicast implementation of the TV, or it maybe some undocumented feature in the TV that doesn’t know how to handle the packets correctly)

We probably won’t be able to fix your router, but we can try to prevent the problem in the TV by changing the UDP port number in the Editor. Could you please try the following:

  1. Start Unreal Editor (make sure that neither Unreal Launcher, nor any other Unreal Engine instance is running on your network)
  2. Go to Edit → Project Settings… → Plugins → UDP Messaging
  3. In the Transport section, change Multicast Endpoint from to and press Enter

This should automatically restart the UDP message transport on port 6283, which hopefully isn’t used by anything in your network.

Please let me know whether the IPTV still freezes while the Editor is running, or whether that fixes the problem, thanks!

So far so good I think that actually worked for the FTV.

Yeah, it doesn’t seem that it would be sending fast enough to cause a problem but it was detected as a flood, I’m thinking maybe that is because both the Launcher and Editor sends the UDP packets so that would be a multiple.

If the plugin is disabled or disable the Enable Transport to disable it there seems to be 10% to 20% editor load speed increase and things seem slightest bit more responsive as well such as when loading blueprints or the settings.

I don’t think I can change the UDP messaging setting for the launcher, I thought maybe I am able to attempt direct packet filtering but the NVG589 packet filtering doesn’t seem to work for it, or set the packets behavior in Unreal Editor using Time to Live but cannot set to 0 and it’s default value is 1.

As far as I know if that setting is to spec then the Time to Live settings would be for IP multicast:
0 is restricted to the same host
1 is restricted to the same subnet
32 is restricted to the same site
64 is restricted to the same region
128 is restricted to the same continent
255 is unrestricted

I will continue troubleshooting but leaving this problem as answered for the FTV portion atleast, thank you for going out of your way to help troubleshoot the problem very appreciated!