G'day randompug,

Welcome to the monastery.

Here's a way to do this that doesn't involve slurp mode or any regexes:

$ perl -Mstrict -Mwarnings -E '
    my @data = (
        "# hostname 123",
        "hostname 123",
        "vlan create vif1 1 2 3 4 5 6",
        "vlan add vif1 7 8 ",
        "ifconfig vif1-1 some data here",
        "ifconfig vif1-2 some data here",
        "..",
        "ifconfig vif1-9 some data here",
        "# hostname 456",
        "hostname 456",
        "vlan create vif5 1 2",
        "vlan add vif5 3 4 5",
        "vlan add vif5 6 7 8 9",
        "ifconfig vif5-1 some data here",
        "ifconfig vif5-2 some data here",
        "..",
        "ifconifg vif5-9 some data here",
    );

    my ($hostname, @hosts, %host_data);

    for (@data) {
        my @fields = split;

        if ($fields[0] eq "hostname") {
            push @hosts => ($hostname = $fields[1]);
        }
        elsif ($fields[0] eq "vlan") {
            $host_data{$hostname}{vlan} += @fields - 3;
        }
        elsif ($fields[0] eq "ifconfig") {
            ++$host_data{$hostname}{ifconfig};
        }
    }

    for (@hosts) {
        say "Hostname: $_";
        say "vlans: $host_data{$_}{vlan}";
        say "ifconfigs: $host_data{$_}{ifconfig}";
    }
'
Hostname: 123
vlans: 8
ifconfigs: 3
Hostname: 456
vlans: 9
ifconfigs: 2
[download]

I don't know where your real data is coming from: you should be able to just change "for (@data) {" to "while (<$file_handle>) {" (or whatever's appropriate) and get the same results. I'll leave you to check the vlan/ifconfig count. Your one instance of ifconifg may be intended for testing or perhaps just a typo.