Windows ipv6 hosts losing default gateway

Roti

Hi. I am using a USG310. Recently my ISP added IPV6 services and I was configuring dual stack IPV4/IPV6. but have run into problems with IPV6 clients.

Initially I found Windows IPV6 clients would lose the default gateway (the link-local address of the USB interface) after a few minutes. I found that turning off SLAAC for the LAN interface seemed to work, but after about 24 hours, the same problem still occurs.

I am connected to a cable modem with IPOE.

I have enabled ICMP6 Router advertisements with the Other configuration bit set and a delegated /64 prefix.

Wireshark of RA packets looked OK I think (although I'm nut sure if the Router Address flag should be set)

Also using Wireshark, I see no Neighbour Advertisement packets being sent. I'm not sure if this is normal.

Is there something I'm missing ?

Thanks.