IPv6 (6in4) Tunnel speeds OpenWRT vs Draytek

Hi all,
I have set up over last day two separate tunnels on tunnelbroker.net. Two different accounts but same server location.

One router with tunnel working on Fibre (FTTP) 100/100 connection and operated via Draytek 2860n

Second router is WRT3200ACM with OpenWRT and connection from Virgin Media 100/10.

Bot connection. Reaching their Download speeds on IPv4. Virgin is even faster.

I set tunnels on both and start testing speed when connected to IPv6 network.

Firstly I thought that due to tunnel the speeds will be slower, but than start comparing.

Draytek on download IPv6 have roughly 86-96Mbps.

OpenWRT on download IPv6 have roughly 6-10Mbps (!!!).

Huge difference.

I know that Draytek is not using OpenWRT but that’s 2012 moder hardware was hi-end Linksys.

Wonder if somebody can advise where to look on improvement, as 10% of original download speed not allow me to use IPv6 daily.

It looks more like some software/hardware incompatibility or settings difference.

Tried MTU change from default 1280 up and down but no speed difference CS.

How is the CPU utilization when you download something?

0.07 on IPv4
0.16 when adding IPv6 and testing speed

Hence no big difference.

Saw a thread here

And here

But nothing help.

IPv6

root@WRT3200ACM:~# iperf3 -c bouygues.iperf.fr -6 -R -p 5207 -t 20
Connecting to host bouygues.iperf.fr, port 5207
Reverse mode, remote host bouygues.iperf.fr is sending
[  5] local XX port 47662 connected to XX port 5207
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  1.30 MBytes  10.9 Mbits/sec                  
[  5]   1.00-2.00   sec  1.46 MBytes  12.3 Mbits/sec                  
[  5]   2.00-3.00   sec  1.88 MBytes  15.8 Mbits/sec                  
[  5]   3.00-4.00   sec  1.60 MBytes  13.4 Mbits/sec                  
[  5]   4.00-5.00   sec  1.98 MBytes  16.6 Mbits/sec                  
[  5]   5.00-6.00   sec  1.40 MBytes  11.8 Mbits/sec                  
[  5]   6.00-7.00   sec  1.80 MBytes  15.1 Mbits/sec                  
[  5]   7.00-8.00   sec  1.53 MBytes  12.9 Mbits/sec                  
[  5]   8.00-9.00   sec  2.02 MBytes  16.9 Mbits/sec                  
[  5]   9.00-10.00  sec  1.70 MBytes  14.3 Mbits/sec                  
[  5]  10.00-11.00  sec  1.62 MBytes  13.6 Mbits/sec                  
[  5]  11.00-12.00  sec  1.86 MBytes  15.6 Mbits/sec                  
[  5]  12.00-13.00  sec  1.62 MBytes  13.6 Mbits/sec                  
[  5]  13.00-14.00  sec  1.53 MBytes  12.8 Mbits/sec                  
^C[  5]  14.00-14.61  sec   768 KBytes  10.4 Mbits/sec

IPv4

root@WRT3200ACM:~# iperf3 -c bouygues.iperf.fr -4 -R -p 5206 -t 20
Connecting to host bouygues.iperf.fr, port 5206
Reverse mode, remote host bouygues.iperf.fr is sending
[  5] local XX port 46968 connected to XX port 5206
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  11.4 MBytes  95.3 Mbits/sec                  
[  5]   1.00-2.00   sec  12.6 MBytes   106 Mbits/sec                  
[  5]   2.00-3.00   sec  12.9 MBytes   108 Mbits/sec                  
[  5]   3.00-4.00   sec  11.6 MBytes  97.1 Mbits/sec                  
[  5]   4.00-5.00   sec  12.5 MBytes   105 Mbits/sec                  
[  5]   5.00-6.00   sec  13.2 MBytes   111 Mbits/sec                  
[  5]   6.00-7.00   sec  13.2 MBytes   111 Mbits/sec                  
[  5]   7.00-8.00   sec  13.3 MBytes   112 Mbits/sec                  
[  5]   8.00-9.00   sec  13.3 MBytes   112 Mbits/sec