why does the service working through ingress fall off after a timeout?

1. there is a deployment interface with an svc of the Clusterip type in the default namespace
2. there is an ingress-nginx-controller deployed on a separate cluster node to the namespace ingress-nginx
3. i created in the default namespace ingress rules

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
 name: ingress
 annotations:
   nginx.ingress.kubernetes.io/rewrite-target: /
spec:
 ingressClassName: nginx
 rules:
   - http:
       paths:
         - path: /
           pathType: Prefix
           backend:
             service:
               name: frontend
               port:
                 number: 8080

on logs ingress-nginx-controller

192.168.199.14 - - [09/Sep/2022:17:34:48 +0000] "GET / HTTP/1.1" 504 160 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:104.0) Gecko/20100101 Firefox/104.0" 374 15.000 [default-frontend-8080] [] 10.244.133.193:8080, 10.244.133.193:8080, 10.244.133.193:8080 0, 0, 0 5.000, 5.000, 5.000 504, 504, 504 865eeff0947be33235e66af5813ce41f 192.168.199.14 - - [09/Sep/2022:17:34:54 +0000] "GET / HTTP/1.1" 400 248 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:104.0) Gecko/20100101 Firefox/104.0" 374 0.000 [] [] - - - - d7b4aa2f0b8472442634a323df8669cf

why do such errors occur?