I think Choroba is right but you can fix it.

  # capture number as well, additional group:
  if ($_ =~ m/UEH(\d+)(.*)=\s+([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-
+9]{1,3})/i) {
      my $number = $1;
      my $file_ip = $3; # ip now third group!
      if ($file_ip =~ m/^11\.\d+\.\d+\.\d+/) {
           my $abc = "UEH".$number . "_ip"; # use $number instead of $
+ii
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I cannot test it but you should be able to...