[SOLVED] Mattermost Websocket Notification

Mattermost installed on Ubuntu 14.04 with nginx as reverse proxy on the same machine and accessible through HTTPS with no issues.
All are behind Caddy Server acting as reverse proxy on different machine.

Settings as per Instructions https://docs.mattermost.com/install/troubleshooting.html#please-check-connection-mattermost-unreachable-if-issue-persists-ask-administrator-to-check-websocket-port are fulfilled properly.

Now, access from outside the network is resulting in websocket errors as below shown,

Please advise on the source of error, It is mattermost or caddy?

Well, the above reported issue has been resolved.