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