Intermittent 502 Errors

[oguruma1218]

I switched from a PfSense router to a Ubiquiti Dream Machine SE. With PfSense, I was using HaProxy on the router, itself. I now am using Nginx Proxy Manager on TrueNAS SCALE Docker/Kubernetes.

I have a LAN and a DMZ network configured on the Ubiquiti router.

The Nginx Proxy Manager is at 192.168.2.1/16:30022/23
The LAN is 192.168.0.0/16
The DMZ is 10.1.1.1/24

Nginx Proxy Manager successfully proxies requests to a web server at 192.168.2.1:9010, but I get intermittent 502 errors with another domain, which is at 10.1.1.21. The web app in question is ERPNext.

It will work fine for maybe 5 minutes or so, then start giving me 502 errors, but only when proxying to the server at 10.1.1.21. I've never had problems with proxyng to 192.168.2.1.