Black screen on WAN streaming.

[luqasz]

Hi.

I have a win10 VM with GPU passthrough. Machine works fine. I can play over LAN. However WAN streaming doesn't work. Moonlight finds and logs in to PC but after switching to fullscreen it just turns black and no picture and audio is streamed.

I've tried over wireguard tunel as well as direct port forwarding. MS Remote desktop works without any problems. One difference between LAN and WAN is MTU size. My ISP PPPoE connections MTU = 1492. LAN = 1500.

In log:

[2023:06:17:15:58:34]: Debug: RAISE: 172.31.20.2:56163 :: AUDIO
[2023:06:17:15:58:34]: Debug: Received ping from 172.31.20.2:56163 [474E4950]
[2023:06:17:15:58:34]: Debug: Start capturing Audio
[2023:06:17:15:58:34]: Debug: Stereo: supported
[2023:06:17:15:58:34]: Debug: Surround 5.1: supported
[2023:06:17:15:58:34]: Debug: Surround 7.1: supported
[2023:06:17:15:58:34]: Debug: Stereo: supported
[2023:06:17:15:58:34]: Debug: Surround 5.1: supported
[2023:06:17:15:58:34]: Debug: Surround 7.1: supported
[2023:06:17:15:58:34]: Debug: Stereo: supported
[2023:06:17:15:58:34]: Debug: Surround 5.1: supported
[2023:06:17:15:58:34]: Debug: Surround 7.1: supported
[2023:06:17:15:58:34]: Debug: Stereo: supported
[2023:06:17:15:58:34]: Debug: Surround 5.1: supported
[2023:06:17:15:58:34]: Debug: Surround 7.1: supported
[2023:06:17:15:58:34]: Debug: Trying audio format [Stereo]
[2023:06:17:15:58:34]: Debug: Found audio format [Stereo]
[2023:06:17:15:58:34]: Error: DuplicateOutput() test failed [0x80070005]

Full log.

[ReenigneArcher]

Probably a port forwarding issue.

[luqasz]

Nope. Same error on WAN as well as on wireguard VPN.

[luqasz]

I suspect MTU since it's smaller on ISP connection. Video streaming is done with UDP. UDP doesn't allow for fragmentation and is lost when packet size is 1500 while it hits smaller MTU size on its path. Anyone knows what packet sizes are used ?

[ns6089]

Anyone knows what packet sizes are used?

It's the moonlight side that sets the packet size, based on MTU if it's available or some heuristics.

This discussion might be relevant. In moonlight-qt you can override it with moonlight.ini, packetSize=1392 being the default for lan streaming.
You can try lower values, do note that this value is not the whole packet, but only the payload, then there's application and transport headers on top of it.

[luqasz]

I've solved my issue. Problem was monitor turned off. GPU needs plugged in monitor (or dummy plug). Dough 🤦