Bug? Client GetResolvedConnectString has port 0

Hi,

I’m using UE5.3 with C++ and Null online service.
Sometimes my client goes through the session join flow and receives a zero port; sometimes not. He’s joining a listen server.

Here’s what I’m logging for two cases:

good:

[2024.01.06-03.35.23:912][  0]TSS: UWidgetMainMenu::JoinGame
[2024.01.06-03.35.23:913][  0]TSS: USessionsGISS::JoinGame
[2024.01.06-03.35.23:914][  0]TSS: FindSessions result = 1
[2024.01.06-03.35.28:924][149]TSS: USessionsGISS::OnFindSessionsComplete 1
[2024.01.06-03.35.28:924][149]TSS: SearchResult: DESKTOP-TOM-1B6990B34964AAB5559940A2231D6777 1/8, IsSessionInfoValid = 1, IsValid = 1
[2024.01.06-03.35.28:924][149]TSS: USessionsGISS::JoinSession
[2024.01.06-03.35.28:924][149]TSS: USessionsGISS::OnJoinSessionComplete GameSession Success
[2024.01.06-03.35.28:924][149]TSS: SessionState = Pending
[2024.01.06-03.35.28:924][149]TSS: ClientTravel 192.168.1.212:7777
[2024.01.06-03.35.28:924][149]TSS: JoinSession result = 1


bad:

[2024.01.06-03.36.34:457][  0]TSS: UWidgetMainMenu::JoinGame
[2024.01.06-03.36.34:457][  0]TSS: USessionsGISS::JoinGame
[2024.01.06-03.36.34:458][  0]TSS: FindSessions result = 1
[2024.01.06-03.36.39:468][150]TSS: USessionsGISS::OnFindSessionsComplete 1
[2024.01.06-03.36.39:468][150]TSS: SearchResult: DESKTOP-TOM-4709A99B480063C36DC4DB87BFAAFEB7 0/8, IsSessionInfoValid = 1, IsValid = 1
[2024.01.06-03.36.39:468][150]TSS: USessionsGISS::JoinSession
[2024.01.06-03.36.39:468][150]TSS: USessionsGISS::OnJoinSessionComplete GameSession Success
[2024.01.06-03.36.39:468][150]TSS: SessionState = Pending
[2024.01.06-03.36.39:468][150]TSS: ClientTravel 192.168.1.212:0
[2024.01.06-03.36.39:468][150]TSS: JoinSession result = 1

You can see that in the bad case, the searchresult shows 0/8 players, and the port is zero. But all the session return codes are good.
Perhaps a race condition. But I don’t see any fault in my client code.

I’m newish to UE so not confident to post this directly as a bug, but does Unreal respond here?

Thanks