Unable to integrate Bot (developed using On-Prem Installation) with Web Client Channel

A followup qn to above - validated above mentioned points i.e. pointing to the right Bot (Bot ID, client ID, secret, Kore API URL etc.,) The JWT token is generated locally.

The issue is, Chat client unable to connect to Kore Bot (ref above image). During client connection process, after JWT grant token authorization call is successful, the rtm url is returned with WS protocol instead of WSS. However just to test, when connected to Kore cloud’s sample Bot, WSS url is returned.

What’s the underlying issue, how to resolve?