Hi all,
We have two sites, one Draytek 2925 at each. One site has a 100Mbit/s fibre leased line with a Cisco 1921 in bridge mode, plus a vDSL line as a backup running at 80/20. The second site has a vDSL line and a fibre wifi connection.

When we configure a LAN to LAN VPN using the site 1 leased line and the site 2 vDSL (as these are the fastest links on each site) the VPN performance is dreadful. If we create a LAN to LAN using the site 1 vDSL and the site 2 vDSL it's as expected given the speed of the lines.

all other traffic via the leased line is fine, it's just when the VPN is running. This line replaced a 50/50 leased line with which this LAN to LAN config worked perfectly, the only thing that changed was a new line and the Cisco router. Since the Cisco router is only bridging the connection between the 21CN and the Draytek (there's no NAT or firewall or routing weirdness going on) it shouldnt interfere with the VPN traffic at all.

We've tried both PPTP and IPSec, dialling out of one to the other and vice versa.

I'm tempted to remove the Cisco completely but I rather like the idea that we can use it as a first line of defence, tweaking the config once we get it working properly to tighten things down a bit.

Anyone seen this issue before? There's bound to be a setting somewhere in the Cisco IOS but I can't stumble around in there all day!

Thanks in advance,

Simon.