--- zzzz-none-000/linux-5.4.213/net/l2tp/l2tp_eth.c	2022-09-15 10:04:56.000000000 +0000
+++ alder-5690pro-762/linux-5.4.213/net/l2tp/l2tp_eth.c	2024-08-14 09:02:13.000000000 +0000
@@ -77,6 +77,8 @@
 	struct l2tp_eth *priv = netdev_priv(dev);
 	struct l2tp_session *session = priv->session;
 	unsigned int len = skb->len;
+
+	skb->skb_iif = dev->ifindex;
 	int ret = l2tp_xmit_skb(session, skb, session->hdr_len);
 
 	if (likely(ret == NET_XMIT_SUCCESS)) {
@@ -119,6 +121,7 @@
 	SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
 	ether_setup(dev);
 	dev->priv_flags		&= ~IFF_TX_SKB_SHARING;
+	dev->priv_flags_ext     |= IFF_EXT_ETH_L2TPV3;
 	dev->features		|= NETIF_F_LLTX;
 	dev->netdev_ops		= &l2tp_eth_netdev_ops;
 	dev->needs_free_netdev	= true;
@@ -150,7 +153,7 @@
 	skb->ip_summed = CHECKSUM_NONE;
 
 	skb_dst_drop(skb);
-	nf_reset_ct(skb);
+	nf_reset_no_generic_ct(skb);
 
 	rcu_read_lock();
 	dev = rcu_dereference(spriv->dev);