Sproxy error- Could not establish connection to ES Repository using "SAP_PROXY_ESR ": Service Unavailable:503

Dear Experts,

When i am trying to execute sproxy from ECC system i am getting below error

Sproxy error- Could not establish connection to ES Repository using "SAP_PROXY_ESR ": Service Unavailable:503

But this is only case for this client because in same server if i login from another client and then try to execute this tcode then it is working.

Previously it was working fine but now its not.

Kindly help for PI7.3

Sumit Jha