Finally took the Draytek router out of the equation and vpn works fine.

So we know that we still got a connection according too wire shark despite being unable to browse or ping via the Draytek.

If I plug directly in the cable modem vpn just works.

vpn with 32 bit operating system works fine.

Alternative vpns have the same problem on 64 bit.

Ubuntu 64 bit is fine.

Disabling udp flood defence makes no difference so has anyone got an idea what to do next????

The other 64 bit pc didn't have gigabit card installed or sent down wan1 or wan2

More testing

disabled load balance policy no difference.

disabled firewall no difference.

Tried direct connection to draytek rather than switch no difference.

Disabled all the vpn rules which I shouldn't need to do since I'm not running a server. No difference.

Well the bizarre problem is down to the 2820. No problems with my new 2920n which works without any trouble at all.

However what the bug is god knows as you can't really get any reliable error messages.

Also why it effects only one 64 bit pc is another strange one.