I am not sure, but suspecting X2 traffic was being routed through S1 once X2 links were not available.
Probably issue is due to packet fragmentation.
Ideally, you should match both eNB and MME to same MTU size.
Yes I figured it out. Thanks!
Does anybody has any document or explaining channel the Qos of NSA 5G end to end, from UE to Spgw to Pcrf?