Istio Upstream connection termination in addition to 503 response code

I have installed istio 1.6.5 and when i try to access my app my GET’s are working fine but POST seem to be failing with below error.

upstream connect error or disconnect/reset before headers. reset reason: connection termination

In the istio-proxy logs i am seeing below
[2020-08-22T03:21:35.423Z] “POST /xxxx HTTP/1.1” 503 UC “-” “-” 667 95 75 - “100.64.224.3” “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.125 Safari/537.36” “4ef899bf-b913-91b3-bbaa-bb919910cef6” “xx.xx.net” “127.0.0.1:8080” inbound|8080|http-web|xx.xx.svc.cluster.local 127.0.0.1:49842 172.16.15.4:8080 100.64.224.3:0 outbound_.8080_._.xx.dev.svc.cluster.local default

I got the same error on 1.6.5 and 1.6.8 upstream connect error or disconnect/reset before headers