I know this is wrong...

It's right, but it's only right within a method where $self is an instance of Device. This means you have to write something like:

package Device;

sub create_communication
{
    my $self = shift;
    return Communication->new( $self->{$serveraddr}, $self->{$port};
}

package main;

my $device        = Device->new( 'device', 'localhost', 8080 );
my $communication = $device->create_communication();
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