This option enables or disables the IPv6 MTU option in Router Advertisements sent by CDRouter on the WAN. If this option is enabled, CDRouter will advertise the IPv6 link MTU. If this option is disabled, the MTU option will not be advertised.
The IPv6 link MTU is the largest IPv6 packet (IPv6 headers + IPv6 payload) that can be transmitted without IPv6 fragmentation on the layer 2 link, and is automatically calculated by CDRouter and configured on each stack that is created during start.
Please see this Knowledge Base article for more information on IPv6 MTU concepts within CDRouter.
This testvar was added in CDRouter 8.1