I was able to fix this error by importing valid trusted certificate into ArcGIS Server admin and setting it to use this certificate. In addition, I had to install SSL certificate from the browser into Trusted Root certificates store as well as export the browser certificate as .cer file and import it as trusted Root certificate into ArcGIS server admin. Restarted ArcGIS server and GeoEvent server services, cleared browser cache and was able to get stream service to work.
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