Custom category page with taxonomy filters

The solution: Add ‘operator’ => ‘AND’, to the tax_query.

'tax_query' => array(

'relation' => 'OR',

array(

    'taxonomy' => 'offer',
    'field' => 'slug',
    'terms' => array($offer),
      'operator' => 'AND',
),

array(

    'taxonomy' => 'network',
    'field' => 'slug',
    'terms' => array($network),
      'operator' => 'AND',
),