Hello Boris,
to reply the first message you need to
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start the web RTC Proxy server: “Start_WebRTCProxy.bat” in Engine\Source\Programs\PixelStreaming\WebRTCProxy\bin
start the signalling web server: “run.bat” in Engine\Source\Programs\PixelStreaming\WebServers\SignallingWebServer
Some people have error message about **Failed to initialize NvEncoder **when using 4k resolution. You can increase the capabilities of encoder by using this parameter -NvEncH264ConfigLevel=NV_ENC_LEVEL_H264_52 when starting your UE application. cf. this documentation Unreal Engine Pixel Streaming Reference | Unreal Engine 5.1 Documentation
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