Okay, here is the behaviour as it currently stands, the modem is a new release !Fritz and doing ipv6 connections with Internode here in Australia, occasionally the link falls over because of our high quality telco we have, but thats another story, so what happens is. When PPP link goes down, router sends RA packet for the prefix with valid lifetime and preferred lifetime of zero. Windows 7 marks prefix as deprecated. When PPP link comes back up, router sends RA packet for same prefix with valid lifetime of 7200 and preferred lifetime of 3600. Windows7 ignores this RA packet and leaves the link deprecated thus not permitting any new ip6 connection. We believe this behaviour is wrong, as per rfc4862 Section-5.5.3 paragraph (e): which states (in part): "If the advertised prefix is equal to the prefix of an address configured by stateless autoconfiguration in the list, the preferred lifetime of the address is reset to the Preferred Lifetime in the received advertisement..." I am led to believe that this forum is a valid input vector for the reporting of bugs in Microsoft Products, if this is not the case perhaps some Microsoft Employee could point this report in the correct direction. -- Rob

There are lab firmwares from AVM for some boxes, which have a workaround for this issue. Microsoft is informed about this and they should already working on a general bugfix.