Someone maybe had similar issues to save my time
In some testings having issue with VoLTE, qci5 bearer is establishing fine but UE is not registering.
On PCAP log I can see only sip register request but no response from IMS.
Only suspicious thing is warning on IP header: ipv6 payload length exceeds framing length.
MTU size is 1500 so that is ok.
Any suggestion or idea for checking?