Perhaps you haven't replaced it correctly? 
use 5.010;
my @lines = ("ip:192.168.243.1", "ip:192.168.243.2" =~
    /(ip:[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})/);
say for @lines;
__END__
ip:192.168.243.1
ip:192.168.243.2

[download]
Do note that ip:192.168.243.2 is in @lines only because the pattern matches the entire string. And do note that "ip:192.168.243.1" is not subject to any matching. In fact, the assignment to @lines is equivalent with: 
my @lines;
$lines[0] = "ip:192.168.243.1";
push @lines, $1 if "ip:192.168.243.2" =~ /(ip:[0-9]{1,3}\.[0-9]{1,3}\.
+[0-9]{1,3}\.[0-9]{1,3})/;

[download]

In reply to Re^5: How regex works in array mode? by JavaFan
in thread How regex works in array mode? by astronogun

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