There’s a glaring bug in gvfs that prevents you from browsing shares using the SMB v2 protocol, which is default in many Linux distributions.
This means if you install a brand new copy of Ubuntu 20.04, set up a share using Samba, and try to connect with it using your file manager, you can’t even connect to a share on your own computer!
To make it work, you have to explicitly change the Samba configuration (/etc/samba/smb.conf) to allow the SMB v1 protocol:
server min protocol = NT1
However, there’s a reason SMB v1 is turned off; it has huge security issues.
So I decided to use SSHFS for simple file sharing instead.