Perspective WebSocket handshake failing with HTTP 503 on a new client

Ignition
1

Hi everyone,

I’m encountering an issue with a new client machine provided by our IT department.

The client can access the Ignition Gateway web interface without any problems, and every other machine on the network can connect to both the Gateway and our Perspective applications seamlessly. The issue occurs exclusively on this specific client.

When attempting to launch a Perspective project from the navigator, the application gets stuck on the loading screen and eventually fails during the WebSocket handshake, throwing an HTTP 503 (Service Unavailable) error.

We’ve reviewed the Ignition Gateway configuration and found no anomalies. Since all other clients connect fine, the Gateway itself doesn't appear to be the problem.

My suspicion is that an endpoint firewall, proxy, SSL inspection, or another network security policy on this specific machine is interfering with the WebSocket connection to the Gateway.

What potential causes should we consider, and what troubleshooting steps or tools would you recommend to pinpoint the issue?

Thanks in advance for your help!

2

A 503 on the upgrade when the gateway web pages load fine on that same machine usually means something in the middle is refusing the websocket, not the gateway. Ignition isn't likely to hand that one machine a 503 while happily serving it everything else.

Quickest way to split it: look at the gateway logs for that client's attempt at the time it failed. If the request never lands in Ignition at all, the 503 came from upstream and you're chasing the proxy.

Then on the machine itself, devtools, network tab, filter WS and look at the response headers on the failed request. Proxies usually stamp their own Via or Server header on error pages they generate, which tells you which box is doing it. SSL inspection setups drop or mangle the Upgrade header fairly often.

Worth diffing the PAC file or proxy settings on that machine against one that works too, since IT handed it over freshly built.