The ONLY thing $/ effects is reading from a filehandle. To change it (and then restore it) inside your while loop has no effect! Its value defines how <FH> operates.

"----switchname----" and the part you actually want to match are on different lines; thus, reading the file one line at a time, you can't match what you want the regex as you've shown. Also, your PortChannel_Num regex doesn't seem to work, since there is no line that consists solely of "port-channel (DIGITS)".

Here is a potential solution:

my %record;

while (<FILE>) {
  if (/----switchname----/) {
    chomp($record{switchname} = <FILE>);
  }
  elsif (/^port-channel (\d+)/) {
    $record{channel} = $1;
  }
}
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