Trouble with Kubernetes Agent cannot connect to KAS server

Hello! I am trying to integrate gitlab with kubernetes. Used this documentation: https://docs.gitlab.com/ee/user/clusters/agent/install/

I got the following errors :

{"level":"warn","time":"2021-12-28T18:43:08.015Z","msg":"GetConfiguration failed","error":"rpc error: code = Unavailable desc = connection error: desc = \"transport: Error while dialing failed to WebSocket dial: failed to send handshake request: Get \\\"https://gitlab.domainname.com/-/kubernetes-agent/\\\": dial tcp: i/o timeout\""}
{"level":"error","time":"2021-12-28T18:43:08.015Z","msg":"Error handling a connection","mod_name":"reverse_tunnel","error":"Connect(): rpc error: code = Unavailable desc = connection error: desc = \"transport: Error while dialing failed to WebSocket dial: failed to send handshake request: Get \\\"https://gitlab.domainname.com/-/kubernetes-agent/\\\": dial tcp: i/o timeout\""}

Network access from nodes to gitlab is available(checked via telnet/curl)

Steps:

1. I added to /etc/gitlab/gitlab.rb

gitlab_kas['enable'] = true

after executed: gitlab-ctl reconfigure

2. In my project created: .gitlab/agents/agentk/config.yaml

gitops:
  manifest_projects:
  - id: "kubernetes/monitoring"
    paths:
    - glob: '/manifests/*.{yaml,yml,json}'

3. Registered a new agent with GitLab(Infrastructure > Kubernetes clusters > Actions > Select an agent > Register an agent) and got the token

4. In K8s executed the below commands:

kubectl create namespace gitlab-kubernetes-agent
kubectl create secret generic -n gitlab-kubernetes-agent gitlab-kubernetes-agent-token --from-literal=token='token_from_register_agent'

Created file the resources.yml:

---
apiVersion: v1
kind: Namespace
metadata:
  name: gitlab-kubernetes-agent
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: gitlab-kubernetes-agent
  namespace: gitlab-kubernetes-agent
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: gitlab-kubernetes-agent
  namespace: gitlab-kubernetes-agent
spec:
  replicas: 1
  selector:
    matchLabels:
      app: gitlab-kubernetes-agent
  template:
    metadata:
      labels:
        app: gitlab-kubernetes-agent
    spec:
      serviceAccountName: gitlab-kubernetes-agent
      containers:
      - name: agent
        # Make sure to specify a matching version for production
        image: "registry.gitlab.com/gitlab-org/cluster-integration/gitlab-agent/agentk:v14.5.0"
        args:
        - --token-file=/config/token
        - --kas-address
        - wss://gitlab.domainname.com/-/kubernetes-agent/
        volumeMounts:
        - name: token-volume
          mountPath: /config
      volumes:
      - name: token-volume
        secret:
          secretName: gitlab-kubernetes-agent-token
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 0
      maxUnavailable: 1
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: gitlab-kubernetes-agent-write
  namespace: gitlab-kubernetes-agent
rules:
- resources:
  - '*'
  apiGroups:
  - '*'
  verbs:
  - create
  - update
  - delete
  - patch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: gitlab-kubernetes-agent-write-binding
  namespace: gitlab-kubernetes-agent
roleRef:
  name: gitlab-kubernetes-agent-write
  kind: ClusterRole
  apiGroup: rbac.authorization.k8s.io
subjects:
- name: gitlab-kubernetes-agent
  kind: ServiceAccount
  namespace: gitlab-kubernetes-agent
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: gitlab-kubernetes-agent-read
  namespace: gitlab-kubernetes-agent
rules:
- resources:
  - '*'
  apiGroups:
  - '*'
  verbs:
  - get
  - list
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: gitlab-kubernetes-agent-read-binding
  namespace: gitlab-kubernetes-agent
roleRef:
  name: gitlab-kubernetes-agent-read
  kind: ClusterRole
  apiGroup: rbac.authorization.k8s.io
subjects:
- name: gitlab-kubernetes-agent
  kind: ServiceAccount
  namespace: gitlab-kubernetes-agent

executed:

kubectl apply -f ./resources.yml -n gitlab-kubernetes-agent

gitlab version: gitlab-ce-14.5.2-ce.0(Omnibus)
k8s version: 1.22.2

I didn't find any errors in the troubleshooting section. What else is worth seeing?