How networking works

PreviewMonitor is built for one job: getting a clean, low-latency picture from your computer to the iPhone sitting next to it. Understanding how it moves data explains why the same network matters so much — and why it stays private.

Local Wi-Fi only

PreviewMonitor streams only over your local Wi-Fi network. The video goes directly from your Mac or PC to your iPhone across your router. It never travels over the internet, and nothing is uploaded to a server in the cloud.

That has two consequences:

• It's private and fast. Your footage stays on your own network, and there's no round-trip to a distant server adding lag.
• Both devices must be on the same network. Your iPhone and your computer have to be on the same Wi-Fi (or the same router) to see each other. This is the single most common reason a connection fails — see Computer doesn't appear.

It is not designed for streaming over the internet, a VPN, or between different networks. Keep both devices on the same local Wi-Fi.

Automatic resolution adaptation

Wi-Fi bandwidth isn't constant — it dips when other devices get busy or when you walk away from the router. PreviewMonitor watches the connection and automatically adapts the resolution to fit the bandwidth available, so the stream keeps flowing instead of freezing.

It also adds forward error correction (FEC), which rebuilds packets lost in transit before they can cause a visible glitch. A little packet loss is invisible thanks to FEC; you'll only notice trouble when loss climbs high (the HUD loss number turns yellow, then red).

You stay in control of the ceiling: the Resolution Limit sets the highest resolution PreviewMonitor will use, and the GOP Mode changes how efficiently the picture is compressed for the network you're on.

Getting the best connection

For the smoothest stream:

• Use 5 GHz Wi-Fi where you can — it's faster and less congested than 2.4 GHz.
• Keep your iPhone reasonably close to the router.
• Avoid busy or crowded networks (a packed café or office Wi-Fi).
• On a weaker network, lower the Resolution Limit and try a shorter GOP Mode.

If the picture stutters, the HUD tells you whether the network is the culprit. See Choppy or laggy stream for a full checklist.