Istio Multicluster DNS lookup of remote service

Hello All
I have setup a istio multicluster mesh using replicated control planes as specified here

Everything is actually working fine but there is one thing i am not able to figure out .
If i execute
curl it works fine.
but if i execute
curl it consistently gives me a 503 with
“upstream connect error or disconnect/reset before headers. reset reason: connection failure” . The dns resolution in either case seems to be fine and it does connect to but in the second case the request never reaches the proxy on the other end as indicated by the istio-proxy logs on the httpbin pod. Any suggestions what might be going on or if its behaving as expected?