macOS to macOS File Sharing - Don't work, try The IT Crowd

 I use File Sharing between two Macs on the same network, both running the latest macOS 13.4 Ventura.

For some strange reason I wasn't able to access one Mac - a Mini - from the other - a MacBook Pro.

As is always the case, the internet solved it for me: -

Fix File Sharing Not Working in MacOS Ventura

TL;DR; turn it off, and on again

Yes, The IT Crowd strikes again

Having said that, Dan Moren, he of Six Colours, acclaimed author AND MacBreak Weekly host, deserves full thanks for directing me to macOS' built-in firewall tool: -

/usr/libexec/ApplicationFirewall/socketfilterfw --listapps

Solving a file sharing mystery: Why one Mac can’t see another 

Whilst the TIOAOA trick worked this time, who knows what I'll need next time ...