diff --git a/src/openvpn/forward.c b/src/openvpn/forward.c
index d8ad0d1..66843b4 100644
--- a/src/openvpn/forward.c
+++ b/src/openvpn/forward.c
@@ -1058,8 +1058,16 @@
              * and return false.
              */
             uint8_t opcode = *BPTR(&c->c2.buf) >> P_OPCODE_SHIFT;
-            if (tls_pre_decrypt(c->c2.tls_multi, &c->c2.from, &c->c2.buf, &co,
-                                floated, &ad_start))
+
+            if ((opcode == P_DATA_V1) && dco_enabled(&c->options))
+            {
+                msg(D_LINK_ERRORS,
+                    "Data Channel Offload doesn't support DATA_V1 packets. "
+                    "Upgrade your server to 2.4.5 or newer.");
+                c->c2.buf.len = 0;
+            }
+            else if (tls_pre_decrypt(c->c2.tls_multi, &c->c2.from, &c->c2.buf,
+                                     &co, floated, &ad_start))
             {
                 /* Restore pre-NCP frame parameters */
                 if (is_hard_reset_method2(opcode))