% psql --host=127.0.0.1/32 --dbname=mattermost --username=mmuser
psql: could not translate host name "127.0.0.1/32" to address: Name or service not known
% psql --host=127.0.0.1/24 --dbname=mattermost --username=mmuser
psql: could not translate host name "127.0.0.1/24" to address: Name or service not known
[I.K >> ] “127.0.0.1/32” is network that includes only “127.0.0.1” while “127.0.0.1” is address.
You specify network in .conf file and use address as argument to psql
