Network and security

Why isolation matters

Prest Server has no login and no password. It serves the stage screens to every device that can reach the host computer, so any tablet can be picked up mid-show. Your protection is the network: only devices you trust should be on it. This applies to Prest Server in REAPER, in Ableton Live, and in Prest.

Any device that can reach the host can:

play, pause, and stop the show, and choose songs, which opens projects in the host without saving the open one;
add, change, and delete songs and setlists, import backups, and wipe the catalog;
set the show library folder, which lets it browse the names of the host computer’s folders;
change the host’s network settings;
in Prest and the next release, move the host’s faders, mutes, and solos in the Mixer view, and add, rename, or delete attachment files in the show library.

Lock This Device and the Rig Pairing Key are not passwords. The lock stops stray touches on one screen; the key keeps rig computers from following the wrong host.

Build a stage network

Use a router or hotspot the band owns and administers.
Set a strong Wi-Fi password.
Connect the host computer by cable where the stage allows it.
Connect only the devices you use on stage.
Keep guest access off, and keep client isolation off for your devices, so they can reach the host.
Rehearse with the same router, cables, and devices you will use at the show.

Other Prest Servers on the network

A host that finds another Prest Server already answering to prest.local becomes its standby and follows it: its host opens the same songs and plays along. That is how a backup computer works, and it is why a shared network is risky.

Set the same Rig Pairing Key on all of your rig’s computers. A host follows only hosts with the same key.
In Prest and the next release, also give your rig its own Rig Name, so that two bands’ rigs on one network each have their own address.
Running only one host? Turning off Announce on the Network (mDNS) keeps it from announcing or following by name. Devices then use its IP address.

Discovery

The leading host announces itself as prest.local on the local network (mDNS). Some routers, hotspots, and devices do not pass these announcements, so keep the host computer’s IP address as the fallback.

macOS 15 and later announces prest.local only if the host app (REAPER, Live, or Prest) has local network access. Allow it when macOS asks, or turn it on in System Settings, under Privacy & Security, Local Network.
A host with several networks (Wi-Fi and cable, or a VPN) may announce itself on the wrong one. Set Stage Network Interface in Setup.

Ports and firewalls

Prest Server listens on port 80 unless you set Server Port in Setup or start the host with PREST_PORT. When the port is taken, it serves on the first free port from 8418 to 8422 and says so at startup, unless you turn Backup Port off.

A firewall on the host computer can block devices even when prest.local resolves. When the operating system asks whether REAPER, the Live bridge (prest-ableton in 0.1.x, prest-server-ableton later), or Prest may accept incoming connections, allow it on private networks only.

With REAPER, PREST_BIND_ADDR set to one of the computer’s IP addresses makes Prest Server listen on that address only.

Diagnostic checklist

The host and the device are on the same private network.
The host is running and shows no Prest Server message.
The IP address works when prest.local does not.
The router’s client isolation and guest network settings let devices reach each other.
The host computer’s firewall allows the host on private networks.
Setup reads Active, not Standby, on the host you meant to use.

For a report, note the Prest Server version (or the Prest version), the host and its version, the operating system, the browser and its version, the address you opened, and the connection state shown.