diff --git a/packet/packet.go b/packet/packet.go
index 0d096ec..31b9fd9 100644
--- a/packet/packet.go
+++ b/packet/packet.go
@@ -84,13 +84,19 @@ func (p *Packet) SetSegSizeForTX() {
 	binary.NativeEndian.PutUint16(p.Control[unix.CmsgLen(0):unix.CmsgLen(0)+2], uint16(p.SegSize))
 }
 
-func (p *Packet) CompatibleForSegmentationWith(otherP *Packet) bool {
+func (p *Packet) CompatibleForSegmentationWith(otherP *Packet, currentTotalSize int) bool {
 	//same dest
 	if !slices.Equal(p.Name, otherP.Name) {
 		return false
 	}
 
+	//don't get too big
+	if len(p.Payload)+currentTotalSize >= 0xffff {
+		return false
+	}
+
 	//same body len
+	//todo allow single different size at end
 	if len(p.Payload) != len(otherP.Payload) {
 		return false //todo technically you can cram one extra in
 	}
diff --git a/udp/udp_linux.go b/udp/udp_linux.go
index 47dc869..f1aa781 100644
--- a/udp/udp_linux.go
+++ b/udp/udp_linux.go
@@ -18,6 +18,9 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+const iovMax = 128 //1024 //no unix constant for this? from limits.h
+//todo I'd like this to be 1024 but we seem to hit errors around ~130?
+
 type StdConn struct {
 	sysFd     int
 	isV4      bool
@@ -66,8 +69,12 @@ func NewListener(l *logrus.Logger, ip netip.Addr, port int, multi bool, batch in
 		return nil, fmt.Errorf("unable to bind to socket: %s", err)
 	}
 
-	msgs := make([]rawMessage, 0, 8192) //todo configure
-	iovs := make([][]iovec, 0, len(msgs))
+	const batchSize = 8192
+	msgs := make([]rawMessage, 0, batchSize) //todo configure
+	iovs := make([][]iovec, batchSize)
+	for i := range iovs {
+		iovs[i] = make([]iovec, iovMax)
+	}
 	return &StdConn{
 		sysFd: fd,
 		isV4:  ip.Is4(),
@@ -220,11 +227,11 @@ func (u *StdConn) WriteBatch(pkts []*packet.Packet) (int, error) {
 	}
 
 	u.msgs = u.msgs[:0]
-	u.iovs = u.iovs[:0]
+	//u.iovs = u.iovs[:0]
 
 	sent := 0
-	const maxIovLen = 48
 	var mostRecentPkt *packet.Packet
+	mostRecentPktSize := 0
 	//segmenting := false
 	idx := 0
 	for _, pkt := range pkts {
@@ -233,19 +240,18 @@ func (u *StdConn) WriteBatch(pkts []*packet.Packet) (int, error) {
 			continue
 		}
 		lastIdx := idx - 1
-		if mostRecentPkt != nil && pkt.CompatibleForSegmentationWith(mostRecentPkt) && u.msgs[lastIdx].Hdr.Iovlen < maxIovLen { //todo math this more good
-
+		if mostRecentPkt != nil && pkt.CompatibleForSegmentationWith(mostRecentPkt, mostRecentPktSize) && u.msgs[lastIdx].Hdr.Iovlen < iovMax {
 			u.msgs[lastIdx].Hdr.Controllen = uint64(len(mostRecentPkt.Control))
 			u.msgs[lastIdx].Hdr.Control = &mostRecentPkt.Control[0]
+
+			u.iovs[lastIdx][u.msgs[lastIdx].Hdr.Iovlen].Base = &pkt.Payload[0]
+			u.iovs[lastIdx][u.msgs[lastIdx].Hdr.Iovlen].Len = uint64(len(pkt.Payload))
 			u.msgs[lastIdx].Hdr.Iovlen++
-			u.iovs[lastIdx] = append(u.iovs[lastIdx], iovec{
-				Base: &pkt.Payload[0],
-				Len:  uint64(len(pkt.Payload)),
-			})
+
+			mostRecentPktSize += len(pkt.Payload)
 			mostRecentPkt.SetSegSizeForTX()
 		} else {
 			u.msgs = append(u.msgs, rawMessage{})
-			u.iovs = append(u.iovs, make([]iovec, 1, maxIovLen)) //todo less garbage
 			u.iovs[idx][0] = iovec{
 				Base: &pkt.Payload[0],
 				Len:  uint64(len(pkt.Payload)),
@@ -263,8 +269,8 @@ func (u *StdConn) WriteBatch(pkts []*packet.Packet) (int, error) {
 			msg.Hdr.Name = &pkt.Name[0]
 			msg.Hdr.Namelen = uint32(len(pkt.Name))
 			mostRecentPkt = pkt
+			mostRecentPktSize = len(pkt.Payload)
 		}
-
 	}
 
 	if len(u.msgs) == 0 {
@@ -287,6 +293,23 @@ func (u *StdConn) WriteBatch(pkts []*packet.Packet) (int, error) {
 			if errno == unix.EINTR {
 				continue
 			}
+			//for i := 0; i < len(u.msgs); i++ {
+			//	for j := 0; j < int(u.msgs[i].Hdr.Iovlen); j++ {
+			//		u.l.WithFields(logrus.Fields{
+			//			"msg_index": i,
+			//			"iov idx":   j,
+			//			"iov":       fmt.Sprintf("%+v", u.iovs[i][j]),
+			//		}).Warn("failed to send message")
+			//	}
+			//
+			//}
+			u.l.WithFields(logrus.Fields{
+				"errno":   errno,
+				"idx":     idx,
+				"len":     len(u.msgs),
+				"deets":   fmt.Sprintf("%+v", u.msgs),
+				"lastIOV": fmt.Sprintf("%+v", u.iovs[len(u.msgs)-1][u.msgs[len(u.msgs)-1].Hdr.Iovlen-1]),
+			}).Error("failed to send message")
 			return sent + offset, &net.OpError{Op: "sendmmsg", Err: errno}
 		}