My client sockets disconnect with a "ping timeout" reason after a few hours of connection and can't connect again

Hi, i'm having a bit of a issue with my project. I'm building an app that will stay opened at all times in the device, with a non-stop connection through the sockets. However lately, all of my sockets disconnect and can't reconnect. I managed to print some logs from the device and here it is :

As you can see on the screenshot, the socket connection starts at around 1:30 AM and then is disconnectd at 7:30 AM, but manages to reconnect each time until 9:14 where it disconnects and then can't reconnect with the reason "ping timeout".

I'm not sure where is the problem here. I'm using Angular 17 with ngx-socket-io version 4.6.1. In my backend i use NestJS with socket-io 4.7.2.

Since this problem that happend this morning i did theses steps to try to fix the problem (i haven't tried it yet) :

• Upgraded my NestJS from v9 (a year old) to v10 (including the @nestjs/websockets package)
• Upgraded socket-io in my NestJS from 4.7.2 to 4.7.5
• Added a pingTimeout of 60000 to my WebSocketGateway (maybe this will fix it ??)

Any idea what could be causing the problem ? Also it's important to note than in my APP i have an interval that tries to connect to the socket every minute just in case it's disconnected, but as you can see on the logs, it can't even reconnect 🤔

Edit: Also important to note that it's only 4 cuccurent connections. With 1 CPU and 2GB of RAM. With NGINX and PM2 for my API.

@darrachequesne

Start with the reported logs and the long-lived Angular 17/ngx-socket-io client against the NestJS backend, then compare disconnect and reconnect behavior with the listed NGINX and PM2 setup. Done means the ping-timeout cause is identified and the client reconnects reliably after hours; the issue provides no named file or test.