diff --git a/unifi/network.go b/unifi/network.go
index 5bccab9..d454738 100644
--- a/unifi/network.go
+++ b/unifi/network.go
@@ -2,9 +2,30 @@ package unifi
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 )
 
+func (dst *Network) MarshalJSON() ([]byte, error) {
+	type Alias Network
+	aux := &struct {
+		*Alias
+
+		WANEgressQOS *emptyStringInt `json:"wan_egress_qos,omitempty"`
+	}{
+		Alias: (*Alias)(dst),
+	}
+
+	if dst.Purpose == "wan" {
+		// only send QOS when this is a WAN network
+		v := emptyStringInt(dst.WANEgressQOS)
+		aux.WANEgressQOS = &v
+	}
+
+	b, err := json.Marshal(aux)
+	return b, err
+}
+
 func (c *Client) DeleteNetwork(ctx context.Context, site, id, name string) error {
 	err := c.do(ctx, "DELETE", fmt.Sprintf("s/%s/rest/networkconf/%s", site, id), struct {
 		Name string `json:"name"`