Error in Websocket API

We are getting the error "Not Connected to WebSocket API while trying to see the data from a Node on Chirpstack Portal. I have attached the screen shot also. Please let me know why is this coming & how to get rid of this.

We are using
chirpstack-network-server Version 3.16.8
chirpstack-application-server Version 3.17.9
chirpstack-gateway-bridge Version 3.14.8
Redis server Version 5.0.7
Postgresql Version 12

Regards
Shashank

The reason is that the web-interface is unable to connect to the websocket API (network issue). Maybe this is caused by a proxy that does not pass the websocket requests correctly?

How to check the Proxy (whether it is passing or not)?

You can open Developer Tools in Chrome to check.