Unable to Join Session using EOS - Error SE_HOST_NOT_FOUND [11001]

[FabioIGF]

I’m currently trying to get a multiplayer session working correctly. I’ve created a plugin that handles matchmaking using Unreal’s Online Subsystem. When I set my DefaultEngine.ini to work with Steam services, everything works as expected.

Now, I’m switching to Epic Online Services (EOS). I followed the official Epic documentation, set up the game dashboard, and configured the DefaultEngine.ini file. I’m using a client policy that implements the default Peer-to-Peer (P2P) configuration provided by EOS.

Current Situation

Here’s what I’ve observed so far:

• Login: The login works correctly, and I get proper authentication.
• Session Creation: I can create an online session (tried both as a lobby and as a direct match), and both cases work fine.
• Session Discovery: I can find the session I created by searching lobbies or presence accordingly.
• Joining the Session: This is where the problem occurs — I cannot join the session.

Relevant Log Excerpt

Here’s the relevant part of the log:

LogSockets: Warning: GetAddressInfo failed to resolve host with error SE_HOST_NOT_FOUND [11001]
LogNet: UNetConnection::Close: [UNetConnection] RemoteAddr: , Name: IpConnection_0, Driver: Name:PendingNetDriver Def:GameNetDriver NetDriverEOSBase_1, IsServer: NO, PC: NULL, Owner: NULL, UniqueId: INVALID, Channels: 3, Time: 2024.10.16-14.57.57
LogNet: UNetConnection::SendCloseReason:
LogNet:  - Result=AddressResolutionFailed, ErrorContext="AddressResolutionFailed"
LogNet: UChannel::Close: Sending CloseBunch. ChIndex == 0. Name: [UChannel] ChIndex: 0, Closing: 0 [UNetConnection] RemoteAddr: , Name: IpConnection_0, Driver: Name:PendingNetDriver Def:GameNetDriver NetDriverEOSBase_1, IsServer: NO, PC: NULL, Owner: NULL, UniqueId: INVALID
LogNet: Error: UEngine::BroadcastNetworkFailure: FailureType = PendingConnectionFailure, ErrorString = Your connection to the host has been lost., Driver = Name:PendingNetDriver Def:GameNetDriver NetDriverEOSBase_1
LogNet: Warning: Network Failure: PendingNetDriver[PendingConnectionFailure]: Your connection to the host has been lost.
LogNet: NetworkFailure: PendingConnectionFailure, Error: 'Your connection to the host has been lost.'

Possible Cause

I found some indications online suggesting that manually opening ports might be necessary, but that’s not feasible for game distribution.

One particularly confusing part relates to a property setting in the config file. I’ve come across the following configurations in different forms:

[/Script/OnlineSubsystemEOS.NetDriverEOS]
bIsUsingP2PSockets=true

[/Script/SocketSubsystemEOS.NetDriverEOS]
bIsUsingP2PSockets=true

[/Script/OnlineSubsystemEOS.NetDriverEOSBase]
bIsUsingP2PSockets=true

I believe this is relevant to my issue, but I’ve tried all possible combinations of these settings without success.

---

Has anyone else encountered this problem or found a solution? I’d appreciate any advice or insights.

[DenverLinkFUN]

I had the same problem, this was the log, so I googled it and went here, don't know if you solved the problem.

LogSockets: Warning: GetAddressInfo failed to resolve host with error SE_HOST_NOT_FOUND [11001]

[ratlover4ever]

bump!!!
If I find out something, i’ll let you guys know too…

[ratlover4ever]

So guys it worked for me!
Unreal Engine version 5.6.0, 5.6.1 (tested and working 09/29/2025)

make sure Online Subsystem EOS Plugin is on, project as C++

get the advanced session plugin to your plugins folder

Add these in Config/DefaultEngine.ini

-----------------------------------------

[/Script/Engine.Engine] 
!NetDriverDefinitions=ClearArray
+NetDriverDefinitions=(DefName=“GameNetDriver”,DriverClassName=“/Script/SocketSubsystemEOS.NetDriverEOSBase”,DriverClassNameFallback=“OnlineSubsystemUtils.IpNetDriver”)
+NetDriverDefinitions=(DefName=“DemoNetDriver”,DriverClassName=“/Script/Engine.DemoNetDriver”,DriverClassNameFallback=“/Script/Engine.DemoNetDriver”)

[OnlineSubsystemEOS]
bEnabled=true

[OnlineSubsystem]
DefaultPlatformService=EOS

[/Script/Engine.GameEngine]
!NetDriverDefinitions=ClearArray
+NetDriverDefinitions=(DefName=“GameNetDriver”,DriverClassName=“/Script/SocketSubsystemEOS.NetDriverEOSBase”,DriverClassNameFallback=“OnlineSubsystemUtils.IpNetDriver”)
+NetDriverDefinitions=(DefName=“DemoNetDriver”,DriverClassName=“/Script/Engine.DemoNetDriver”,DriverClassNameFallback=“/Script/Engine.DemoNetDriver”)

[/Script/SocketSubsystemEOS.NetDriverEOSBase]
bIsUsingP2PSockets=true

[/Script/OnlineSubsystemEOS.EOSSettings]
CacheDir=CacheDir
DefaultArtifactName=EOSTESTING
RTCBackgroundMode=
TickBudgetInMilliseconds=0
bEnableOverlay=True
bEnableSocialOverlay=True
bEnableEditorOverlay=True
bPreferPersistentAuth=False
TitleStorageReadChunkLength=0
+Artifacts=(ArtifactName=“EOSTESTING”,ClientId=“YOUR_CLIENT_ID_HERE”,ClientSecret=“YOUR_CLIENT_SECRET_HERE”,ProductId=“YOUR_PRODUCT_ID_HERE”,SandboxId=“YOUR_SANDBOX_ID_HERE”,ClientEncryptionKey=“YOUR_ENCRYPTION_KEY_HERE”)
-AuthScopeFlags=BasicProfile
-AuthScopeFlags=FriendsList
-AuthScopeFlags=Presence
+AuthScopeFlags=BasicProfile
+AuthScopeFlags=FriendsList
+AuthScopeFlags=Presence
bUseEAS=True
bUseEOSConnect=True
bUseEOSRTC=True
bMirrorStatsToEOS=True
bMirrorAchievementsToEOS=True
bUseEOSSessions=True
bMirrorPresenceToEAS=True
bUseNewLoginFlow=False
SteamTokenType=Session
NintendoTokenType=NintendoServiceAccount

-----------------------------------------

(Below, I am not sure if these settings affect anything)

bUseNewLoginFlow=False

(Below, I am not sure if this should be in /Script/Engine.Engine or /Script/Engine.GameEngine)

!NetDriverDefinitions=ClearArray
+NetDriverDefinitions=(DefName=“GameNetDriver”,DriverClassName=“/Script/SocketSubsystemEOS.NetDriverEOSBase”,DriverClassNameFallback=“OnlineSubsystemUtils.IpNetDriver”)
+NetDriverDefinitions=(DefName=“DemoNetDriver”,DriverClassName=“/Script/Engine.DemoNetDriver”,DriverClassNameFallback=“/Script/Engine.DemoNetDriver”)

Generate visual studio files by deleting the intermediate, binary, saved, etc

Build solution in visual studio

open uproject and make sure to do this (This will show in dev portal in the GameServices→Multiplayer→Lobbies):

Also make sure the dev portal permissions are like this:

sorry for the number of edits.. its my first time helping out to the forums, i owe this community so its time i tried as well to help