Some intermediate servers (proxy/gateway/firewall/router/etc) will answer a request from the browser on behalf of the server. If this happens frequently and you are unable to change the intermediate server to avoid this (supporting 2 minute connections is a good start) you can use

top.noodle.ajax.ignoreMasquerading=true;

use that as a last resort as it can cause further UI interference.

Even if Masquerading is not an issue sometimes just a blocked port can be an issue and one can check if the server and client are using the same IP;

the IP of the domain name in the web browser address bar

nslookup noodle.example.intra.net

should match one of the IPs of the server:

ip address show #Linux

ipconfig /all

Less commonly other network devices can cause problems and they can be listed by tracing the IPs between the client and server:

traceroute $IP #Linux

tracertr %IP