...
my $Config = Config::Tiny->new;
$Config = Config::Tiny->read( $ini_path , 'utf8' );
say Dumper \%Config;
my $domain = $Config{$sub_hash}->{'domain'};
my $username = $Config{$sub_hash}->{'username'};
my $password = $Config{$sub_hash}->{'password'};
my $port = $Config{$sub_hash}->{'port'};
...
Global symbol "%Config" requires explicit package name (did you forget
+ to declare "my %Config"?) at template_stuff/html4.pm line 215.
Global symbol "%Config" requires explicit package name (did you forget
+ to declare "my %Config"?) at template_stuff/html4.pm line 216.
Global symbol "%Config" requires explicit package name (did you forget
+ to declare "my %Config"?) at template_stuff/html4.pm line 217.
Global symbol "%Config" requires explicit package name (did you forget
+ to declare "my %Config"?) at template_stuff/html4.pm line 218.
...
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Config::Tiny returns a (blessed) reference to a hash, which is stored in the scalar $Config, so there is no %Config hash available. Both \%Config and $Config{$sub_hash} are however attempting to access a hash named %Config. Instead of Dumper \%Config, do Dumper $Config, and instead of $Config{$sub_hash}, say $Config->{$sub_hash}, and it should work. See perlreftut and perlref.