Index: sys/dev/netmap/netmap.c
===================================================================
--- sys/dev/netmap/netmap.c
+++ sys/dev/netmap/netmap.c
@@ -446,6 +446,7 @@
 #include <net/if.h>
 #include <net/if_var.h>
 #include <net/bpf.h>		/* BIOCIMMEDIATE */
+#include <net/if_vlan_var.h>	/* VLAN_CAPABILITIES */
 #include <machine/bus.h>	/* bus_dmamap_* */
 #include <sys/endian.h>
 #include <sys/refcount.h>
@@ -1019,6 +1020,9 @@
 			D("BUG: netmap on while going to delete the krings");
 		}
 
+		/* Restore any capabilities disabled when put into netmap mode */
+		na->ifp->if_capenable |= na->cap_restore;
+
 		na->nm_krings_delete(na);
 	}
 
@@ -2214,11 +2218,26 @@
 	}
 
 	if (nm_kring_pending(priv)) {
+
+		/* We do not support passing 802.1q VLAN IDs through the rings
+		 * so disable hardware tag stripping and generation, as well
+		 * as LRO/TSO/checksum offloading over a VLAN interface.
+		 */
+		const unsigned inhibit_cap = IFCAP_VLAN_HWTAGGING |
+			IFCAP_VLAN_HWTSO | IFCAP_VLAN_HWCSUM | IFCAP_TSO |
+			IFCAP_RXCSUM | IFCAP_TXCSUM | IFCAP_RXCSUM_IPV6 | IFCAP_TXCSUM_IPV6 | IFCAP_LRO;
+
+		/* Save existing capabilities to restore when we leave netmap mode */
+		na->cap_restore = na->ifp->if_capenable & inhibit_cap;
+		na->ifp->if_capenable &= ~inhibit_cap;
+
 		/* Some kring is switching mode, tell the adapter to
 		 * react on this. */
 		error = na->nm_register(na, 1);
 		if (error)
 			goto err_del_if;
+
+		VLAN_CAPABILITIES(na->ifp);
 	}
 
 	/* Commit the reference. */
Index: sys/dev/netmap/netmap_kern.h
===================================================================
--- sys/dev/netmap/netmap_kern.h
+++ sys/dev/netmap/netmap_kern.h
@@ -740,6 +740,7 @@
 	 * packets from the network stack when netmap is active.
 	 */
 	int     (*if_transmit)(struct ifnet *, struct mbuf *);
+	int	cap_restore;
 
 	/* copy of if_input for netmap_send_up() */
 	void     (*if_input)(struct ifnet *, struct mbuf *);