imc Express requires websockets for interactive communication in both directions to enable collaboration. Websockets are supported in all major browsers since 2014.

imc Express only uses encrypted websocket connections. These are supported by most proxy servers and firewalls (the TLS tunnel enables low-level end-to-end TCP communication through the HTTP proxy). Unfortunately, there are still old proxy servers that cannot handle websockets. Even more often, the problem is due to firewall configurations that generally prohibit websockets.

To find out if you are affected by this problem, please use this test: websocketstest.com

If your firewall prohibits websockets, ask your administrator to unblock the domain app.imc-express.cloud for encrypted websocket connections (wss://).