Summary:
I use the standalone Steam Link app on my Windows desktop to remotely control my Steam Deck when it's in desktop mode, to avoid having to plug it into a keyboard/mouse/monitor. This has worked perfectly until recently.

Since June or July, Steam Link for Windows is unable to connect to my Steam Deck while the Steam client is running on the same PC. It only connects if I either:

• Close Steam first on my Desktop, then launch Steam Link normally (works perfectly), or
  
• Run Steam Link as Administrator while Steam is open (connects, but video performance is broken — laggy, maybe due to software decoding fallback?)

Expected behavior:
Steam Link should connect to the Steam Deck and stream video smoothly regardless of whether Steam is running on the same machine.

Actual behavior:

With Steam open on my Desktop:

• Steam Link sees the Deck but cannot connect unless launched with admin rights
  
• When run as admin, connection succeeds — but video is slow/choppy

With Steam client closed on my Desktop, Steam Link works perfectly

Environment:

• Steam Link version: 1.3.15.384 from https://media.steampowered.com/steamlink/windows/latest/SteamLink.zip
  
• Windows version: Windows 10 Pro
  
• Steam Deck OS: Up to date as of July 2025
  
• Network: Both devices on wired gigabit Ethernet

Steps to Reproduce:

• Launch Steam on Windows desktop
  
• Launch Steam Link (non-admin) → fails to connect to Deck
  
• Launch Steam Link as admin → connects, but streaming is sluggish
  
• Quit Steam completely
  
• Launch Steam Link (non-admin) → works fine, full performance

Troubleshooting performed:

• Cleared remote.vdf config files on both Deck and desktop
  
• Disabled firewall/AV for testing
  
• Compared behavior with a separate laptop (no Steam client installed), connects to the Deck without issues
  
• Observed performance drop when Steam Link is run as admin (video decode fallback?)