Hi @elizabeth.wills,
the services on both platforms run in different non-default ports, but we have nginx that proxies all services to a common https (port 443) port.
Given that all firewalls allow ports 443 and 80, then I think your firewall is blocking WebSocket Connections. We use WebSockets extensively. Could you check that with your IT team?
I think they are allowing http:// and https:// protocols, but now allowing ws:// or wss://, which are used for WebSocket connections.