QCI5 bearer establishing but UE not registering

Hello Experts.
Someone maybe had similar issues to save my time :slightly_smiling_face:

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?

Where did you capture PCAP, MTU is not 1500 at UE it would be in 13xx range (unless jumbo frames are in network), check the configuration received for IMS apn for the MTU size.
This problem is usually MTU related.

1500 is set on eNB side, got from operations.
1420 is on PCAP without the header.

SIP packet is more than 1500 bytes, it must be reassembled in the PCAP.
And check you get all details in the SIP packet, it is not truncated.