As per RFC 4861 Router advertisement message
format, Source Address MUST be the link-local address
assigned to the interface from which this message is sent.
Since SMF was not sending it as per RFC, certain
phones were not completing the procedure of stateless
IPv6 address autoconfiguration mentioned in
3GPP TS 23.401 version 15.12.0 Release 15, section 5.3.1.2.2
Sukchan Lee
Supreeth Herle