diff --git a/samples/net/vlan/Kconfig b/samples/net/vlan/Kconfig
index 22ef6b07f8b..88ae77ef983 100644
--- a/samples/net/vlan/Kconfig
+++ b/samples/net/vlan/Kconfig
@@ -53,4 +53,12 @@ config NET_SAMPLE_IFACE3_VLAN_TAG
 	  Set VLAN (virtual LAN) tag (id) that is used in the sample
 	  application.
 
+config NET_SAMPLE_IFACE_MY_IPV6_PREFIXLEN
+	int "IPv6 address prefix length for the interfaces"
+	default 64
+	range 0 128
+	help
+	  Set the IPv6 address prefix length (netmask) for the interfaces
+	  that is used in the sample application.
+
 source "Kconfig.zephyr"
diff --git a/samples/net/vlan/prj.conf b/samples/net/vlan/prj.conf
index ffce904005f..20ea9f0627b 100644
--- a/samples/net/vlan/prj.conf
+++ b/samples/net/vlan/prj.conf
@@ -32,6 +32,9 @@ CONFIG_NET_CONFIG_NEED_IPV6=y
 CONFIG_NET_CONFIG_NEED_IPV4=y
 CONFIG_NET_CONFIG_SETTINGS=y
 
+# IPv6 prefix len
+CONFIG_NET_SAMPLE_IFACE_MY_IPV6_PREFIXLEN=64
+
 # First ethernet interface will use these settings
 CONFIG_NET_CONFIG_MY_IPV6_ADDR="2001:db8::1"
 CONFIG_NET_CONFIG_PEER_IPV6_ADDR="2001:db8::2"
diff --git a/samples/net/vlan/src/main.c b/samples/net/vlan/src/main.c
index 7b7736f71a2..cfcff4c2643 100644
--- a/samples/net/vlan/src/main.c
+++ b/samples/net/vlan/src/main.c
@@ -42,7 +42,7 @@ static int setup_iface(struct net_if *iface, struct net_if *vlan,
 {
 	struct net_if_addr *ifaddr;
 	struct in_addr addr4;
-	struct in6_addr addr6;
+	struct in6_addr addr6, netaddr6;
 	int ret;
 
 	ret = net_eth_vlan_enable(iface, vlan_tag);
@@ -63,6 +63,20 @@ static int setup_iface(struct net_if *iface, struct net_if *vlan,
 				ipv6_addr, vlan);
 			return -EINVAL;
 		}
+
+		net_ipv6_addr_prefix_mask((uint8_t *)&addr6,
+					  (uint8_t *)&netaddr6,
+					  CONFIG_NET_SAMPLE_IFACE_MY_IPV6_PREFIXLEN);
+
+		if (!net_if_ipv6_prefix_add(vlan, &netaddr6,
+					    CONFIG_NET_SAMPLE_IFACE_MY_IPV6_PREFIXLEN,
+					    (uint32_t)0xffffffff)) {
+			LOG_ERR("Cannot add %s with prefix_len %d to interface %p",
+				ipv6_addr,
+				CONFIG_NET_SAMPLE_IFACE_MY_IPV6_PREFIXLEN,
+				vlan);
+			return -EINVAL;
+		}
 	}
 
 	if (IS_ENABLED(CONFIG_NET_IPV4)) {
diff --git a/samples/net/vlan/vlan-setup-linux.sh b/samples/net/vlan/vlan-setup-linux.sh
index 28892a7cd44..275910c9728 100755
--- a/samples/net/vlan/vlan-setup-linux.sh
+++ b/samples/net/vlan/vlan-setup-linux.sh
@@ -49,11 +49,11 @@ ip link add link ${IFACE} name ${VLAN_NAME_PREFIX}.200 type vlan id 200
 ip link set ${VLAN_NAME_PREFIX}.100 up
 ip link set ${VLAN_NAME_PREFIX}.200 up
 
-ip -6 addr add ${PREFIX_1_IPV6}::2 dev ${VLAN_NAME_PREFIX}.100
+ip -6 addr add ${PREFIX_1_IPV6}::2/${PREFIXLEN_1_IPV6} dev ${VLAN_NAME_PREFIX}.100
 ip -6 route add ${PREFIX_1_IPV6}::/${PREFIXLEN_1_IPV6} \
    dev ${VLAN_NAME_PREFIX}.100
 
-ip -6 addr add ${PREFIX_2_IPV6}::2 dev ${VLAN_NAME_PREFIX}.200
+ip -6 addr add ${PREFIX_2_IPV6}::2/${PREFIXLEN_2_IPV6} dev ${VLAN_NAME_PREFIX}.200
 ip -6 route add ${PREFIX_2_IPV6}::/${PREFIXLEN_2_IPV6} \
    dev ${VLAN_NAME_PREFIX}.200