Quest 3 Unity preview — persistent lag/low FPS via Air Link AND Link Cable

Hi everyone,

I'm struggling with a very frustrating issue previewing my Unity Scene on my Meta Quest 3, and after a lot of troubleshooting I'm out of ideas. Hoping someone here has seen the same pattern.

When I hit Play in Unity with the Quest 3 as the PC-VR headset, the preview is laggy, stutters heavily, and runs at a very low frame rate, sometimes so bad it's impossible to test anything. Sometimes, even the Quest Link menu is already very laggy. The strange part is that it's not consistent:

- Sometimes the preview starts perfectly fine.

- Then if the HMD goes inactive (I take it off while editing in Unity for a bit) and I put it back on, the lag comes back.

- Sometimes it's bad from the very first Play.

- Occasionally it just works for a whole session.

What I've already ruled out / tried

- Air Link / network: I initially thought it was bandwidth, but my WiFi is over 300 Mbps, and my PC is on 1 Gbps Ethernet to the router. Hard to see how that's the bottleneck.

- **Link Cable:** Switching to a wired Link Cable makes **no difference** — same lag pattern. So it's not a wireless issue.

- OculusDash.exe: I read that other Quest 3 Link users have had laggy performance caused by OculusDash.exe. Adding a firewall rule to block it sometimes  fixes the lag. Then the problem comes back, and toggling the rule on/off sometimes helps again. Not reliable.

- Meta Horizon Link app: Keeping the Meta Horizon Link desktop app open and clicking on the currently active device sometimes resolves the lag. Again — sometimes, not always.

- Audio bug (bonus): Even when the preview is running fine, the audio output keeps switching on its own between HMD speakers and PC speakers, without me selecting that. Happens mid-session.

- Meta XR All-in-One SDK / Simulator: I tried installing it so I could use the XR Simulator and bypass the HMD preview, but it caused compilation errors in my Unity project, so I had to remove it completely. I'm currently only able to preview through the HMD directly.

- PC requirements: I've verified my PC meets all the Meta PC VR minimum/recommended specs (specs below).

Environment

- Unity 6.3 LTS (6000.3.5f2)

- Meta Quest 3, latest firmware

- Meta Quest Link / Meta Horizon Link PC app, latest version

- Both Air Link and Link Cable tested — both show the issue

My PC specs:

- OS: Windows 11 Pro 64-bit (Build 26200)

- CPU: AMD Ryzen 5 3600X (6 cores / 12 threads, 3.8 GHz base)

- GPU: NVIDIA GeForce RTX 5060 (8 GB VRAM), driver 32.0.15.9186

- RAM: 16 GB DDR4 (2× 8 GB Crucial BLS8G4D240FSBK @ 2400 MHz)

- Network: 1 Gbps Ethernet (Realtek PCIe GbE), WiFi 300+ Mbps

- Also listed as a display adapter:"Meta Virtual Monitor" (driver 5.3.57.114) — installed by the Meta software

I'd really appreciate any pointers! This is slowing down my iteration loop in Unity. Thanks!