Intermittent white screen with “Failed to load resource: net::err_connection_reset” in console log

I have a WordPress website which is on it’s own server with the only other site on there being the DEV version of the site.

When browsing around the website (back and front end) I sometimes get a blank white screen with no error on the screen and no fatal errors in the log, only a “Failed to load resource: net::err_connection_reset” message in the console log.

I refresh the screen and the website acts as if there is nothing wrong.

I’ve tested on different networks and PCs but still get the issue. I’m using Sucuri but have chatted with them and they provided me with the logs and I can see my IP isn’t being blocked at any point.

I browse around the dev site which isn’t going through Sucuri firewall or a caching plugin and I don’t get the issue.

I’ve done a lot of Googling but some people saying its a website issue and some people saying its a local browser/firewall issue so I have no idea what it could be.

Does anyone have any ideas or suggestions on how to fix or even to debug the issue further?