First I think I'd check that

my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/snmp_ports_sl
+ot20.txt" );
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succeeded. Perhaps something like

my $cfg_file = q{$ports_ini_dir/snmp_ports_slot20.txt};
my $cfg = Config::IniFiles->new( -file => $cfg_file)
  or die qq{cant open *$cfg_file*: $!};
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