WebSocket message with Arduino MKR 1010 using WiFiNINA and ArduinoHttpClient libraries
I needed to use port 80.

I got a hint from wikipedia:


  The communications are done over TCP port number 80 (or 443 in the case of TLS-encrypted connections), which is of benefit for those environments which block non-web Internet connections using a firewall.


https://en.wikipedia.org/wiki/WebSocket

Switched to port 80 and it works!