In a 2024 post, developer Freddie W documented the difficulty of getting two game instances to communicate over Steam Networking on the same machine. That experience reflects a broader pattern. From direct development experience working with Unreal's Steam Online Subsystem, testing a Steamworks-integrated dedicated server locally involves several overlapping requirements, and a home network isn't set up to meet all of them.

The answer isn't a Steam workaround. It's rethinking what the test environment should be in the first place: online.

What Good Multiplayer Testing Actually Looks Like

Before getting into the Steam-specific constraint, it helps to set the standard you're testing against.

Good multiplayer testing has three properties. It runs on the same infrastructure you'll ship with, so environment differences don't hide bugs until release. It runs under real network conditions, so latency-sensitive issues surface in development rather than post-launch. And it forces correct configuration early, so the gap between your local setup and a packaged build doesn't silently accumulate until it breaks at the worst moment.

Local testing with two windows on the same machine fails all three. Localhost has zero latency and zero packet loss. Your editor build behaves differently than your packaged server build. And what passes locally may not reflect what players encounter at all.

Good testing isn't just "does it connect." It's "does it connect, on real infrastructure, under real conditions, with the config you'll actually ship."

Why Steamworks Local Testing Is Particularly Hard

The core issue is that a locally hosted Steamworks dedicated server needs more than correct code to become testable. Several things have to align at once.

Server authentication comes first. The dedicated server must initialize with Steam via SteamGameServer_Init and complete its log-on sequence before clients can successfully complete the connection handshake. If that authentication hasn't fully resolved, the connection fails without a clear error telling you why.

Server browser visibility is where the home network creates the biggest wall. Valve's master servers need to be able to reach your locally hosted server from the public internet to list and verify it. A standard home router's NAT configuration blocks those inbound requests by default. Your server may appear in the local LAN server list while remaining completely invisible in the internet server browser, even with ports manually opened. This is the most common reason developers spend hours debugging configuration that is technically correct.

Port binding adds another layer. The server needs both a game port and a query port open. The query port is separate, and forgetting it breaks server browser registration and can silently break the connection handshake, even when the game port appears reachable.

None of these are unusual requirements in isolation. Together, on a home network, they create a setup that's genuinely difficult to validate without real infrastructure.

The Steamworks Workaround Exists, But It's Not Enough

The practical workaround most developers land on is direct IP connection: bypass the server browser entirely and connect client to server by raw IP address. This sidesteps the master server visibility problem and works reasonably well for basic functional tests on a local network.

It adds its own requirements. Direct IP connection through the Steamworks networking layer needs correct ISteamNetworkingSockets API configuration and explicit relay opt-out to avoid unintentionally routing traffic through Valve's infrastructure. The single-machine case adds further friction: server and client competing for the same Steamworks socket bindings can cause initialization failures. This is the specific issue Freddie W documented, and the same community thread confirms it: on one machine, workarounds compound.

Direct IP gets you to a connection. It doesn't get you to production parity or real network conditions. And the underlying configuration still has to be correct before any of it works.

The Solution: Testing on Actual Dedicated Servers

The fix isn't a Steam workaround. It's removing the server from the Steam client equation entirely.

A dedicated server has no Steam ID. It's not a Steam client. It doesn't need a logged-in account to run. When your local machine connects to a dedicated server deployed in the cloud, the Steamworks constraint becomes trivially simple: one machine, one Steam client, one account. Exactly the setup Steam was designed for.

This is also the right mental model for development. Your client talks to a server. The server is infrastructure. That's the architecture your players will experience, and testing against it from day one means what works in development actually ships.

It also validates configuration in the right context. The Unreal Steam Online Subsystem setup, the DefaultEngine.ini entries, the steam_appid.txt placement, all of it gets exercised against a real packaged server build, not just inside the editor. Config drift, the quiet accumulation of differences between local and production environments, stops before it starts.

Edgegap's game server orchestration deploys dedicated servers across 615+ locations worldwide. Your test server is outside the Steam client constraint and running under real network conditions, at a real edge location, with real latency between client and server. The bugs you find are the bugs that matter.

Getting There in Minutes, Without Build-From-Source

The historical objection to dedicated server testing during active development is setup time. Building Unreal from source, configuring Linux server targets, packaging, uploading: the process could consume most of a day before the first test runs.

Edgegap's Docker Extension for Unreal Engine removes that barrier. It skips the build-from-source requirement entirely, handles the Linux server build and Dockerfile automatically, and deploys a live dedicated server to Edgegap's edge network in minutes. No DevOps expertise required. No second machine.

The result is a test environment that meets all three properties from the start: same infrastructure as production, real network conditions, correct configuration forced from the first test. And unlike the two-machine workaround or the IPC name trick, this workflow scales. Every developer on the team tests the same way, against the same kind of server, from the first day of multiplayer development.

The test environment isn't throwaway work either. The server you deploy to test is the server you ship with.

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This article draws on direct development experience working with Unreal's Steam Online Subsystem, and references a blog post by Freddie W published on What is TsFreddie Doing? in September 2024, and Valve's Steamworks API documentation. All rights in the original content are owned by their respective owners.