I also had this problem, and what ended up getting me on the right path is N.Chipper's answer, but I want to add a caveat.

His NGINX example would not work because the retries there do not repeat 10 times for example. What they do is they pass it forward to the next server. There are hacky ways to get around that by making an infinite loop reffering to nginx from inside nginx, and then limiting that, but it's not great, and you have less control over timeouts.

In Traefik it also does not work. This is what they say in the docs: As soon as the server answers, the middleware stops retrying, regardless of the response status.

So if a server responds with 502, it passes it forward.

The only solution that worked was the Caddy example provided there.