Now the link appears to be up. But I am still unable to update my appliance.
As per
http://openvpn.net/index.php/access-server/download-openvpn-as-vm/202.html?osfamily=Virtual%20Appliance%20Windows%20(VHD)&ex=1
last command returns the error
dpkg-deb: `openvpn-as-1.8.5-Ubuntu8.i386.deb' is not a debian format archive
dpkg: error processing openvpn-as-1.8.5-Ubuntu8.i386.deb (--install):
subprocess dpkg-deb --control returned error exit status 2
Errors were encountered while processing:
openvpn-as-1.8.5-Ubuntu8.i386.deb