Don't start debugging your radvd if your Virtual Guest doesn't work correctly with IPv6. All the VMware products have a problem with IPv6 route advertisements over a briged network connection going over a wireless link.
Your virtual machine will get an IPv6, but will not get the IPv6 gateway.

To disable IPv6 in Ubuntu add the following line blacklist ipv6 in the /etc/modprobe.d/blacklist file. If you don't want to reboot you can try to remove the IPv6 kernel module with the sudo rmmod command. But that failed with me as the module was in use.

VMWare filed this as bug #26078, communities forum link