[Bug] Multiplayer Pokémon Scarlet connection error

[Fotia13]

Description of the issue

Hello, I think I need help for multiplayer with Pokémon Scarlet.
Context:

• I'm in the same LAN as my brother
  ,
• Ryujinx is allowed in the Windows Firewall rules on both computers and both inbound (TCP & UDP) and outbound (all protocols)
• We have both the same Ryujinx version (tried with 1.2.76 and canary 1.2.161)
• Same prod.keys
• Same Firmware version (18.1.0)
• Same Pokémon Scarlet [0100A3D008C5C000] with the same update 3.0.1 (the canary I used doesn't show the version) and also same DLC
  
• Not the same save, we both created a new save file
• RyuLDN with Guest Internet Access/LAN Mode on (I read the guide afterwise)
• Vsync is on on both computer
• 51 Worldwide Games [010047700D540000] worked flawlessly in local multiplayer with this setup

So with this setup we managed to connect with Union Circle like 1-2 minutes and then got connection error and everytime we try to reconnect same error in like 2 seconds.
Host PoV:

Guest PoV:

We've tried with Guest Internet Access/LAN Mode off doesn't work (because we are in the same LAN I guess).
We've tried with ldn_mitm with Guest Internet Access/LAN Mode on and off and it does the same as RyuLDN.
So I looked the logs and I read HLE.OsThread.9 ServiceLdn ConfigureAccessPoint: Failed to open a port with UPnP for P2P connection. Proxying through the master server instead. with RyuLDN so I looked at my router parameters and UPnP IGD is activated with version 2 and Parsec works.

I created a new user on both computer and it doesn't change the problem.
And then I finally managed to get the ability to read and read that RyuLDN is only over the internet and Pokémon Scarlet isn't on the list of LAN Mode Games.
So I connected my computer to my phone in access point mode and changed the interface in Ryujinx to my phone and same error.

Is there any way for us to play Pokémon Scarlet in multiplayer?
And also why UPnP doesn't work for me, I have a Freebox révolution with Freebox OS 4.8 (a french router) and it did the same with my phone but I won't be surprised if my phone doesn't do UPnP.

Reproduction steps

Launch Ryujinx with 2 computers with the following parameters: RyuLDN and Guest Internet Access/LAN Mode off.

Play Pokémon Scarlet on both, one create a club room and the other join the first with a 4 digits code then wait and connection error should appear.

Log file

Ryujinx_Canary_1.2.161_2024-12-28_22-23-15.log

OS

Windows 10 64 bits

Ryujinx version

1.2.76 and canary 1.2.161

Game version

3.0.1

CPU

AMD Ryzen 7 5700X 8 core

GPU

NVIDIA GeForce RTX 3060 Ti

RAM

32GB

List of applied mods

None

Additional context?

Sometimes I have to open ports on my router like when I host a minecraft server.

[Vudjun]

If you're running on the same network, changing the mode to ldn_mitm should work for you. The connection will then be direct between the two PCs. The current implementation of uPnP seems to have issues with many routers, idk why.

[Fotia13]

Nope same issue with ldn_mitm, I put this parameter to the 2 computers:

and after 2-3 minutes we get the same error,
Host:
Host-Ryujinx_Canary_1.2.186_2024-12-30_19-07-12.log

Guest:
Guest-Ryujinx_Canary_1.2.186_2024-12-30_19-08-26.log

Also I tried with Ryujinx_Canary_1.2.186 on both computers this time.

[Fotia13]

Still the same with Guest Internet Access/LAN on

Host-Ryujinx_Canary_1.2.186_2024-12-31_01-48-24.log
Guest-Ryujinx_Canary_1.2.186_2024-12-31_01-49-17.log