Disable flow control as it's broken - https://github.com/xelerance/xl2tpd/issues/133

Index: control.c
--- control.c.orig
+++ control.c
@@ -1506,7 +1506,7 @@ static inline int expand_payload (struct buffer *buf, 
     l2tp_log (LOG_DEBUG, "%s: payload, cid = %d, Ns = %d, Nr = %d\n", __FUNCTION__,
          c->cid, new_hdr->Ns, new_hdr->Nr);
 #endif
-    if (new_hdr->Ns != c->data_seq_num)
+    if (0)
     {
         /* RFC1982-esque comparison of serial numbers */
         if (((new_hdr->Ns < c->data_rec_seq_num) &&
