I have gotten used to relying on accessing shared drives on my desktop machine from my laptop.
Somehow, between OS upgrades, the default user name used to connect remotely changed from my usual account to ‘Guest’.
I first started noticing this issue when file transfers from one machine to the other suddenly started returning several errors about insufficient access rights and ’empty’ file names not being able to be removed from one machine.
Fortunately, the solution required to make sure I selected ‘Connect as…’ and changed the user name to use the right account. Unfortunately, the option to save that account and password in the keychain was repeatedly ignored… which required to use ‘Connect as..’ the next time I tried to connect remotely again.
In order to fix that Keychain issue, I had to open the rarely used Keychain utility (Applications -> Utilities -> Keychain access). There, I found several old and no longer relevant entries in dire need of a cleanup. Among them, an entry with the name of my remote machine.
Deleting the Keychain entry and login again to the remote drive restored the right name and password for that shared drive.