NDI/OSC only working in localhost

[Windows // 4.26 // OSC & NDI Plugin]

Hey there!
I have some issues getting data/video from other machines in my local network.

I can see incoming Messages in my OSC Monitor but not in Unreal. If i echo these messages to localhost, then i´m able to catch the messages.

Same but different. I can see Incoming Video in my Studio Monitor bu t not in Unreal. With sources created on local machine (Test Pattern), there are no issues.

Are there any Network settings i missed? (I already turned off my Firewall)
Do Unreal only works on certain Ports?

Thanks to you all!