# TrueNAS Collabora app: custom Web UI port causes 502 Bad Gateway **URL:** \ **Category:** Installation & Configuration\ **Created:** [September 24, 2026, 5:09pm UTC](https://forum.collaboraonline.com/t/truenas-collabora-app-custom-web-ui-port-causes-502-bad-gateway/5063 "2026-09-24T17:09:23Z")\ **Posts on this page:** 1\ **Showing post:** 3
**Author:** ![darshan](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.collaboraonline.com/darshan/32/2230_2.png) [@darshan](https://forum.collaboraonline.com/u/darshan)\ **Post date:** [September 28, 2026, 12:07pm UTC](https://forum.collaboraonline.com/t/truenas-collabora-app-custom-web-ui-port-causes-502-bad-gateway/5063/3 "2026-09-28T12:07:35Z")
Hello, Thank you for the detailed report. Your analysis is correct. This is a bug in the TrueNAS app template, not in Collabora Online itself. When a certificate is configured, the app puts an nginx container in front of Collabora. The template starts coolwsd on the WebUI port you choose (–port 30002), but the bundled nginx configuration always proxies to collabora:9980. The two only line up when the WebUI port is 9980, which is why your test fixed it. The app is maintained by the TrueNAS team at [GitHub - truenas/apps · GitHub](https://github.com/truenas/apps) (under ix-dev/stable/collabora), so the fix needs to happen there. The simplest correction is for the nginx configuration to proxy to the configured WebUI port instead of the fixed 9980. Please open an issue on that repository and include your findings; the nginx and coolwsd lines you quoted are exactly what they need. Until it is fixed, you can keep the WebUI port at 9980, or disable the certificate option and terminate TLS in your own reverse proxy. I hope this helps Thanks Darshan --- _[View the full topic](https://forum.collaboraonline.com/t/truenas-collabora-app-custom-web-ui-port-causes-502-bad-gateway/5063)._