Well, one obvious problem is that you didn't escape the backslash, and ended up with \+ which escapes the plus sign.

I wouldn't use a compilicated regex, but a simple split.

{
    my @chunks  = split /\\/ => $file, 3;
    my $network = join  "\\" => @chunks [0, 1];
    my $path    = $chunks [2];
    ...
}
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Abigail