Often you think a task will take 5 minutes, say for example cloning a colleagues repo and running it locally, often reality thinks differently.

After installing the dependencies I assumed I could jump right in and test:

npm start

<RealityJoinsTheChat>

 at Server.emit (events.js:412:35)
at emitErrorNT (net.js:1358:8)
at processTicksAndRejections (internal/process/task_queues.js:82:21) {
code: 'EADDRINUSE',
errno: -48,
syscall: 'listen',
address: '::',
port: 5000
}

</RealityJoinsTheChat>

When running UI5 locally approuter defaults to port 5000, this is typically an unbound port. However on MacOS Monterey:

lsof -nP +c 15 | grep LISTEN …

ControlCenter 731 i804190 35u IPv4 0x9387225c821a7f85 0t0 TCP *:7000 (LISTEN)
ControlCenter 731 i804190 36u IPv6 0x93872257b9d7d77d 0t0 TCP *:7000 (LISTEN)
ControlCenter 731 i804190 37u IPv4 0x9387225c821a6a35 0t0 TCP *:5000 (LISTEN)
ControlCenter 731 i804190 38u IPv6 0x93872257b9d7de7d 0t0 TCP *:5000 (LISTEN)

The feature using port 5000 is part of AirPlay. For me the solution was simply to disable AirPlay in sharing.

Sharing Service

Hopefully this saves someone else the time it took me to find the root of the issue.