When trying to connect to the PC (on local network), Moonlight successfully shows "Starting Steam" messages, Steam starts to load on the PC, then Moonlight shows a message saying:
Connection Error
Failed to start RTSP handshake (error 552)
Check your firewall and port forwarding rules for port(s):
TCP 48010
UDP 48000
UDP 48010
This message appears, and Moonlight fails to connect to the PC, despite the PC having received the connection from Moonlight to start running Steam (usually in Big Picture Mode).
Solution
I discovered by accident that this error goes away if Steam is already running when you try to connect with Moonlight.
It appears as if the RTSP handshake is failing, seemingly, because Steam is not fully loaded on the PC at the time that Moonlight is attempting to initiate the handshake; perhaps a longer handshake-timeout of some sort could help? Not sure, just guessing.
If I simply start Steam manually, either in "normal" windowed mode or Big Picture Mode on the PC, then connect with Moonlight, it works perfectly. Note that during all this, Steam is still "running" in the system tray icon on Windows; its the foreground app window that is not running at the time when Moonlight prompts the PC to "start Steam".
Perhaps we can have some sort of note about this type of error behavior added to the docs here;
Describe the bug
When trying to connect to the PC (on local network), Moonlight successfully shows "Starting Steam" messages, Steam starts to load on the PC, then Moonlight shows a message saying:
This message appears, and Moonlight fails to connect to the PC, despite the PC having received the connection from Moonlight to start running Steam (usually in Big Picture Mode).
Solution
I discovered by accident that this error goes away if Steam is already running when you try to connect with Moonlight.
It appears as if the RTSP handshake is failing, seemingly, because Steam is not fully loaded on the PC at the time that Moonlight is attempting to initiate the handshake; perhaps a longer handshake-timeout of some sort could help? Not sure, just guessing.
If I simply start Steam manually, either in "normal" windowed mode or Big Picture Mode on the PC, then connect with Moonlight, it works perfectly. Note that during all this, Steam is still "running" in the system tray icon on Windows; its the foreground app window that is not running at the time when Moonlight prompts the PC to "start Steam".
Perhaps we can have some sort of note about this type of error behavior added to the docs here;
Steps to reproduce
Attempt to connect to the PC with Moonlight while Steam is not running
Affected games
NA
Other Moonlight clients
PC
Moonlight adjusted settings
Yes
Moonlight adjusted settings (please complete the following information)
none
Moonlight default settings
Yes
Gamepad-related connection issue
No
Gamepad-related input issue
No
Gamepad-related streaming issue
No
Android version
Android 11 ; SHIELD Android TV Software Version 9.1.1
Device model
Nvidia Shield TV (2015)
Server PC OS version
Windows 11
Server PC GeForce Experience version
3.27.0.120
Server PC Nvidia GPU driver version
546.33 desktop win10 win11 64bit international dch whql
Server PC antivirus and firewall software
Windows Defender
Screenshots
No response
Relevant log output
No response
Additional context
No response