[Dovecot] Cannot access IMAP from other computer on network

I am a newcomer to Dovecot so apologies if this is elementary.

I want to set up dovecot to allow other computers on my home network to read emails on my desktop via IMAP. This computer is called arcadia.

dovecot is running and I can access the mail on the same computer with mutt -f imap://ac@localhost.

If I use the above line on a different computer in the network it says "authenticaing 'PLAIN'" and then "logging in ..", then "login failed" and cuts out.

In /etc/dovecot/dovecot.conf I have set

disable_plaintext_auth = no

I have no idea how to proceed further.

Anthony Campell