/ (?m:             # not capture, multiline
   .*              # skip anything
   [\w\.-]+        # the 'device' name part
   \s? (?:\(config[^\)]*\))?     # random '(config...)' part
   \s? [\$#?>]                  # real prompt end part
   \s? (?:\(enable\))? \s*      # random '(enable)' part
  $)
/x
[download]

You're missing the '\' escape of the '.' in the device part. It's supposed to be a hostname like thing: foo-bar.baz10.com and needs to match a literal period '\.'.

You also may need to set the timeout a bit longer depending on how long it takes to download.

What you really want to do is know the device name in advance, or get it from the last-prompt after you login. Then replace the [\w\.-]+ part of the regex with the actual name of the device.

You're missing the '\' escape of the '.'

The dot isn't special inside of a character class, so no escaping required:

$ perl -E 'say "matched" if "foo-bar.baz" =~ /^[\w.-]+\z/'
matched
$ perl -E 'say "matched" if "foo-bar:baz" =~ /^[\w.-]+\z/'
[download]

The second case (with ':' in place of '.') doesn't match, because the (unescaped) dot in the pattern stands for a literal dot, not "any character" as it would outside of character classes.

Looks like the problem had to do with the regex being slightly changed from the recommended Net::Telnet::Cisco prompt. The prompt should be changed from this:

Prompt => '/(?m:.*[\w.-]+\s?(?:\(config[^\)]*\))?\s?[\$#>]\s?(?:\(enab
+le\))?\s*$)/'
[download]

To this:

Prompt => '/(?m:^[\w.-]+\s?(?:\(config[^\)]*\))?\s?[\$#>]\s?(?:\(enabl
+e\))?\s*$)/'
[download]

The key difference being the ^ that marks the beginning of the line