Enabling remote Zen Streaming with a CLI argument

Juniper Bouchard — Thu, 18 Dec 2025 06:13:00 GMT

Note that this was written with UE 5.5 in mind. More recent versions of ZenLaunch can install Zen Server as a Windows service and can use a different set of settings for it. However, I still think that this can be useful when manually starting Zen Server.

Enabling Zen Streaming via the config

If you work with Unreal Engine, chances are that you'll eventually be testing on other devices than your PC, whether it be a mobile device, a Steam Deck, etc. Eventually, your game may become quite large, making packaging and deploying to other devices rather inconvenient and slow. Thankfully, Epic has introduced Zen Streaming, which can use your PC's Zen Server (the new DDC and cooked output storage system) to stream assets directly over the network. This means that you can deploy only the binaries and keep the cooked content on your development machine, making deployments much faster. However, for this to work, the documentation recommends that you add the following to your project's DefaultEngine.ini:

[Zen.AutoLaunch]
LimitProcessLifetime=false
AllowRemoteNetworkService=true

Why it's not ideal

This... isn't great, for a couple of reasons:

You need to open the editor at least once for it to launch Zen
If submitted to source control, all of your team will have it enabled, potentially causing security issues
If you launch Zen Server via ushell (.zen start), it will not pick up that configuration
- It will, however, pick up the settings in the engine's BaseEngine.ini, but editing that is even worse in my opinion

Modifying the ZenLaunch program

It would be nice if you could, say, start Zen Server with ushell and conditionally enable remote streaming, like this:

.zen start -- -AllowRemoteNetworkService

Fortunately, it only requires a simple 2 line modification to enable this. In Engine/Source/Developer/Zen/Private/ZenServerInterface.cpp, at line 1244 (as of 5.5), change the following:

if (!InSettings.bAllowRemoteNetworkService)
{
	Parms.Append(TEXT(" --http-forceloopback"));
}

to this:

// @YOURCOMPANY_CHANGE [IMPROVEMENT] by juniper.bouchard - BEGIN: Add a parameter to allow Zen Server to be launched allowing remote connections
const bool bAllowRemoteNetworkServiceOverride = FParse::Param(FCommandLine::Get(), TEXT("AllowRemoteNetworkService"));
if (!InSettings.bAllowRemoteNetworkService && !bAllowRemoteNetworkServiceOverride)
{
	Parms.Append(TEXT(" --http-forceloopback"));
}
// @YOURCOMPANY_CHANGE [IMPROVEMENT] - END

Now once you recompile ZenLaunch (which ushell will do for you when attempting to start Zen Server), you'll be able to use the -AllowRemoteNetworkService parameter to allow remote devices to use your development machine as a Zen Streaming server.

Juniper Bouchard's blog

Enabling remote Zen Streaming with a CLI argument

Enabling Zen Streaming via the config

Why it's not ideal

Modifying the ZenLaunch program