Players getting Network Connection Lost when joining public lobby

thrax207 · June 22, 2025, 10:19am

Thanks for the update @BrendannnD .
What you could do is delay matchmaking disabling after 15-30 min for example (not sure how fast your game bugs), but this might help your metrics a little bit more.

Could you share content of the .uefnproject file, for example if your project is called ZoneWars, the file would be ZoneWars.uefnproject + could your share island settings matchmaking stuff? (Team size, team config etc)

I am especially interested in the matchmaking what it says, trying to see if there’s anything off here.

BrendannnD · June 22, 2025, 10:27am

"dataSets":
	{
		"matchmaking":
		{
			"maxPlayers": 3,
			"maxTeamCount": 100,
			"maxTeamSize": 3,
			"maxSocialPartySize": 3,
			"allowJoinInProgress": true,
			"allowSquadFillOption": false,
			"islandQueuePrivacy": "Unrestricted",
			"minPlayers": 1,
			"overtimePlayerTarget": 1,
			"queueMainDuration": 5,
			"queueOvertimeDuration": 5,
			"useSkillBasedMatchmaking": false,
			"ratingType": "",
			"version": 1
		},
		"experimental":
		{
			"sceneGraph":
			{
				"bIsSceneGraphSystemAllowed": false
			}
		}
	},

thrax207 · June 22, 2025, 10:37am

@BrendannnD
I don’t see anything out of the ordinary with that matchmaking, looks similar to mine and I tried basically all settings.

another thing I’m trying to explore; is the project we created for example X months ago bugged? I’m moving over my ‘heavy’ devices etc to a fresh project.

I used this tycoon code before but I did quite some changes to be honest compared to previous versions. My other previous versions never had this issue (2 projects), so I’m trying to rule out if it’s my code.

Do you notice between your tycoons any correlation with date of creation? And did you change a lot in between with your code ?

Edit, just moved over my devices to fresh new project + level, nothing in the map except spawn pads, didnt change island settings from original FN template. Added the 3 devices + did some basic configuring of it (just 1 empty base basically)

Ran a private code (since couldnt use launch session)

After 1hour, I tried to rejoin with my other acc, but it created a new session.
I joined the party, to make sure I get in the same session, and received Network Connection Lost

I’m now going to delete the custom devices and see if I still run into the error.

Jimbohalo10 · June 22, 2025, 12:18pm

hi @thrax207 ,
Earlier posted a Matchmaking log.

Matchmaking Flow Summary: 

PVP TYCOON - 17s 429ms
Flow finished successfully

Parameters:
	Island: 
	MatchmakingGroup:
		thrax207 (Local) - Ready
		VastHorizonsFN - Not Ready
	Metadata:
		LinkId [Mnemonic=[9524-0220-6933] Version=[latest]] 
		WorldId [World [None] WorldName [None] WorldOwnerId [INVALID] IsJoinable [Unjoinable]] 
		ProductModes [None] 
		SessionId [Session Id [469433b576fb4466bb463eba93435cc5] Join Info [IslandJoinability [Joinable] SessionKey [B7641A61B8B6423AAD8C4FC934BC4A98]]] 
		Privacy [Fill] 
		Region [EU] 
		MatchmakingId [D09A31DA4B26D4BB943C3E8E951DAA3F]
	UnrankedSet [Invalid],
	UnrankedIslands [Mnemonic=[9524-0220-6933] Version=[6]],
	UnrankedFallback [**Invalid**],
	RankedSet [**Invalid**],
	RankedIslands [Empty],
	RankedFallback [**Invalid**],
	bGracefullyUpgraded [False],
	PlaylistName [NoPlaylist]
	
	Party Leader: VastHorizonsFN

Steps:
	Matchmaking Begin - Immediate - Success:
	Hidden Delay - Immediate - Success:
		No member uses the 'Matchmaking Delay' setting, continuing...
	Refresh DAD - Immediate - Success:
		UGC mode, no playlist update required
	Refresh MCP Profiles - 743ms - Success:
	Validity Checks - Immediate - Success:
	Preload Athena - Immediate - Success:
		No need to preload athena for this mode, discarding prior athena references
	QosUpdate - 1s 73ms - Success:
	Anticheat - 679ms - Success:
	Keychain Update - Immediate - Success:
	Install Game Features - Immediate - Success:
	Clear Caches - Immediate - Success:
	Clean Up Old Sessions - Immediate - Success:
		No Session Found When Cleaning Up Old Sessions
	Clean Up Old Console Sessions - Immediate - Success:
		Not on Console So No Need To Clean Up Old Conslole Sessions
	Request Reservation - 3s 773ms - Success:
		Joining existing session. SessionId [SessionId: 469433b576fb4466bb463eba93435cc5]
		Attempting to join VastHorizonsFN
		Joined VastHorizonsFN
	Request Moderator Permissions - Immediate - Success:
	Wait For World Session - Immediate - Success:
		No world set
	Find World Session - Immediate - Success:
		No world set
	Request World Token - Immediate - Success:
		No world token required
	Call Matchmaking Service - Immediate - Success:
		Joinable session so no need to request a session.
	Find Session - 299ms - Success:
		Succesfully Found Session [Id: 469433b576fb4466bb463eba93435cc5]. Local user number: 0. Ping: 9999ms
	Query Session Encryption Key - 233ms - Success:
		Querying encryption key for thrax207 (Primary player) with Id: MCP:1c72ad98d5894588974ce45b42e3f1b9
	Query User Session ID Tokens - 234ms - Success:
	Reserve Position Within Existing Session - Immediate - Success:
		Already reserved for full party before finding session
	Refresh Auth Tokens - Immediate - Success:
	Join Session - 265ms - Success:
		Player With Id [1c72ad98d5894588974ce45b42e3f1b9] Joined Session [GameSession]
	Download Content - 3s 827ms - Success:
		Starting Download
		Content Beacon Readiness Changed To: Server is generating manfiests for consumption by the client.
		Content Beacon Readiness Changed To: Server is generating manfiests for consumption by the client.
		Content Beacon Readiness Changed To: In the progress of mounting the content.
		Content Beacon Readiness Changed To: Client is up to date with server content.
		Content Beacon Disconnect Requested
		Content Beacon Readiness Changed To: Client is up to date with server content.
		Content Beacon Readiness Changed To: In the progress of disconnecting from the host.
	Wait For Server Initialization - 2s 265ms - Success:
	Wait For Non Local Party Members Before Travel - Immediate - Success:
		Island has joinable session. Not waiting for non local party members before travel
	Wait For Travel Animation To Complete - 4s 2ms - Success:
		Travel animation started
		Travel animation finished
	Loading Screen - 35ms - Success:
	Travel To Session - 1ms - Success:
		Starting travel for controller 0 to session GameSession
[2025.06.16-13.37.07:833][482]LogQos: [UQosRegionManager::RegisterQoSSettingsChangedDelegate] delegate was replaced
[2025.06.16-13.37.07:833][482]LogFortPlaytimeManager: [3e62] Unblocking idle states from source Matchmaking

You will see hightlighted as invalid

UnrankedFallback [Invalid],
RankedSet [Invalid],
RankedIslands [Empty],
RankedFallback [Invalid],
bGracefullyUpgraded [False],
PlaylistName [NoPlaylist]

For me there is something wrong.
Its not a Ranked
If its not a ranked game should should this be True or false not invalid?

	UnrankedSet [Invalid],
	UnrankedIslands [Mnemonic=[9524-0220-6933] Version=[6]],
	UnrankedFallback [Invalid],

So if its an UnrankedIsland as it has a valid code
Why is UnrankedSet [Invalid] Should Invalid be something like True/ False or Empty.

Is there a Matchmaking parameter for setting Ranked or Unranked game?

Cannot see the parameters for above in the log any where

NeverSit · July 1, 2025, 12:30pm

Hey has there been found a fix for this issue?
The same is happening in a map im trying to publish, its set to unlisted for now

Flak · July 7, 2025, 1:54pm

Not yet, the team is still checking into this.

blau.222 · July 11, 2025, 3:03pm

do you recommend us to wait with posting our maps untill this is solved? Feels risky to post a 4 month project without knowing if it will flop due to a bug or not.

YouTube_Giova · July 26, 2025, 12:53am

Hello! Im having the same issue. Has been resolved?

X_TyFighter_X · July 28, 2025, 6:42am

Having the same issue on our farm map

5234-9939-0856

Its always public lobbies that fail, private works fine

Flak · July 28, 2025, 11:35am

Checking for status.

BrendannnD · July 29, 2025, 7:34pm

Any update on this?

Jimbohalo10 · July 29, 2025, 10:00pm

(post deleted by author)

ClickGamesFN · July 30, 2025, 3:33pm

Based on my experience, this issue is happening on all platforms. I saw the same error while testing on Xbox and Switch. Some players from PS5 also reported the same error.

thrax207 · August 3, 2025, 7:51pm

MAJOR UPDATE
@Flak we finally figured out what went wrong, this is HUGE since I found also a problem in parallel for Scene Graph.

See post here with reproduction steps: Topics tagged unreal-engine

ManteigaStudio · August 12, 2025, 12:07am

Any news? Same error here