L2U Handover is low in 4G ZTE

Hi guys,

I'm facing a issue in 4G ZTE. Handover from 4G(900-3Mhz) to 3G(900-2100) is very bad. HOSR is 89%. The main reason is "Number of Re-estabilshment to Source eNodeB When Outgoing inter-RAT(LTE->UTRAN) Handover Execution" (C373312713). 3G side is normal (no congestion, no alrm....). This issue happended on wholoe network. Please give a suggestion to solve this cause. Thanks for your help!

Hi,
This is a old or new issue?, share the below parameter.
A1, A2, B2 parameters event threshold (RSRP, RSRQ),