5G Xn-based Handover — Why Did It Fail?

A premium subscriber on a highway complains that their call drops every time they travel between the cells served by gNB-01 (10.50.0.5) and gNB-02 (10.50.0.6). Both gNBs are connected to the same AMF (10.45.0.1) and SMF (10.45.0.3). Xn is configured between them and the link is up — ping, SCTP heartbeats, everything looks healthy. The UE has one active PDU session (id=7) on S-NSSAI 01-000000 (eMBB, SST=1) with DNN `internet`. The operations team has captured the Xn-C (SCTP port 38422) and NGAP traces during an active UE's handover attempt. Your job: find where in the handover procedure it fails, what the XnAP cause value tells you about the root cause, and recommend the correct long-term fix. Hint: the answer is already visible in a very early packet in the capture — long before the HandoverRequest is ever sent.