WebSocket connections fail on Tomcat 9.0.56 with Docker

STEPS TO REPRODUCE

1. Start an XWiki DockerImage      

docker run -d --name xwiki -p 38080:8080 -v /root/xwiki-n:/usr/local/xwiki -e DB_USER=root -e DB_PASSWORD=123456 -e DB_DATABASE=xwiki -e DB_HOST=192.168.220.83:31101 192.168.220.84/xwiki/xwiki:13.10.0

1. Install Extensions Realtime WYSIWYG Editor 13.10
2. If the case, go to Global Administration: WYSIWYG Editor,set default DEFAULT WYSIWYG EDITOR （Realtime WYSIWYG Editor)
3.  Edit a page in Wiki mode and observe the JS console

EXPECTED RESULTS

The user is connected to the collaborative session.

ACTUAL RESULTS

The connection to the collaborative session doesn't succeed and in browser's JS console there are some error messages (see screenshots attached):

{type: 'TIMEOUT', message: 'waited 30000ms'}
M @ loader.js:638
Promise.then (async)
.....
wysiwygEditor.js:212 Realtime is disallowed. Quitting

WebSocket connection to 'ws://localhost:38080//websocket/xwiki/netflux' failed: 

In XWiki console, when the server starts, there is the no warning displayed about websocket