Can't find a session

Hello,

I have some troubles with the session system. I have Menu with 2 buttons, one to create a session and the other to join the session. They are bound like this :

It seems that it correctly creates session as the host correctly move in the Main level. But when I try to join, it fails on the Find Sessions node and it prints this warning in the logs :

LogOnline: Warning: OSS: Failed to send discovery broadcast SE_NO_ERROR

I dug a bit in the engine sources and when it search for sessions, it fails in LANBeacon.cpp at line 179 when it calls BroadcastPackets method which leads to this function :

bool FLanBeacon::BroadcastPacket(uint8* Packet, int32 Length)
{
	int32 BytesSent = 0;
	UE_LOG_ONLINE(Verbose, TEXT("Sending %d bytes to %s"), Length, *BroadcastAddr->ToString(true));
	return ListenSocket->SendTo(Packet, Length, BytesSent, *BroadcastAddr) && (BytesSent == Length);
}

After passing in SendTo method BytesSent is equal to -1 and so false is returned. I tried to dig a bit more but the SendTo method is called continuously even if I don’t host a session or try to find one.

As you can see in the screenshot, I’ve set the “listen” option in the Open Level node.
I have disabled the “Auto connect to server” option in the Editor Preferences.
In the Build.cs file I added these lines:

PrivateDependencyModuleNames.Add("OnlineSubsystem");
PrivateDependencyModuleNames.Add("OnlineSubsystemNull");

and in DefaultEngine.ini I added :

[OnlineSubsystem]
DefaultPlatformService=Null

I don’t understand what I’m missing here. I’m pretty sure it’s something like a checkbox not checked or an option not correctly set, as always x)

I also tried Advanced Sessions plugin but I ran in the exact same problem.

Edit 1: I tried to disable my firewall, but it doesn’t worker neither…

Try to use a higher value for MaxResults in FindSessions.
As you are using OnlineSubsystemNull, I’m not really convinced this is actually the problem, but just in case, I think you should try (when using OnlineSubsystemSteam, it can definately be the reason, so… maybe it can happen with NULL too ?)