The answer is here: Reddit - Dive into anything
From rgb-freak:
You have to edit the config.json in Engine\Source\Programs\PixelStreaming\WebServers\SignallingWebServer\
You must add a STUN and a TURN server
in the configuration as it described
under
Unreal Engine Pixel Streaming Reference | Unreal Engine 5.3 Documentation.
This server won’t work behind a NAT.
They must be public reachable in the
Internet.For STUN i took
stun:stun1.l.google.com:19302For TURN i rent the cheapest cloud
instance at
Günstiges Cloud Hosting (3 EUR /
Month) and followed this install
instructions:
https://www.nomachine.com/AR07N00894Now it works like a charm. Only
clients behind proxys have connection
problems with the TURN server. Maye I
change the TURN server software as
mentioned here:
javascript - Coturn/turnserver : error 437: Mismatched allocation: wrong transaction ID (WebRTC) - Stack Overflow
In my case, I just changed this line in the Start_AWS_WithTURN_SignallingServer.ps1 file and it worked:
$peerConnectionOptions = “{ "“iceServers"”: [{"“urls"”: ["“stun:stun1.l.google.com:19302"”,"“turn:” + $PublicIp + “:19303"”], "“username"”: "“PixelStreamingUser"”, "“credential"”: "“Another TURN in the road"”}] }”