Re: L2TP too slow

The type apparently is 'tun':

admin@ubnt# set firewall options mss-clamp interface-type ipsec
Interface type must be "pppoe", "pptp", "tun", "vti", or "all"

So now according to your suggestion I have:

admin@ubnt# show vpn l2tp remote-access mtu
 mtu 1392

admin@ubnt# show firewall options
 mss-clamp {
     interface-type tun
     mss 1352
 }

This results in Windows sending a segment length of 1406, with retransmissions, no good. Then I reduced the mss to 1252. The segment size did not change. The clamp has no effect.

Then to better match the SonicWall, I reduced to:

admin@ubnt# show vpn l2tp remote-access mtu
 mtu 1338

admin@ubnt# show firewall options
 mss-clamp {
     interface-type tun
     mss 1298
 }

This resulted in segment size of 1352 (exactly the SonicWall). But, still retransmissions, whereas the SonicWall does not have this problem.

I tried your QOS solution, and a few variations. In all cases it actually made the problem worse.

So it looks like clamping does not work / has no effect. The size follows the l2tp MTU but not the clamp. How can I get the clamp to work?