Did you ever get a resolution to this, I am stuck with exactly the same issue.

I got this working in the end, terminating the SSL at nginx (passthrough on the load balancer) and allowing it to reverse-proxy the data to the apps with sticky sessions. For anyone else stuck on this, here are my manifests - hope they help:

nginx-ingress-loadbalancer-service.yaml

kind: Service
apiVersion: v1
metadata:
  name: ingress-nginx
  namespace: ingress-nginx
  annotations: 
    # See https://github.com/digitalocean/digitalocean-cloud-controller-manager/blob/master/docs/controllers/services/examples/README.md#accessing-pods-over-a-managed-load-balancer-from-inside-the-cluster
    service.beta.kubernetes.io/do-loadbalancer-name: "api.example.com"
    service.beta.kubernetes.io/do-loadbalancer-hostname: "api.example.com"
    service.beta.kubernetes.io/do-loadbalancer-protocol: "http"
    service.beta.kubernetes.io/do-loadbalancer-tls-passthrough: "true"
    service.beta.kubernetes.io/do-loadbalancer-sticky-sessions-type: "cookies"
    service.beta.kubernetes.io/do-loadbalancer-sticky-sessions-cookie-name: "jammydodger"
    service.beta.kubernetes.io/do-loadbalancer-sticky-sessions-cookie-ttl: "60"
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
spec:
  externalTrafficPolicy: Local
  type: LoadBalancer
  selector:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
  ports:
    - name: http
      port: 80
      protocol: TCP
      targetPort: http
    - name: https
      port: 443
      protocol: TCP
      targetPort: https

---

ingress.yaml

# Define Ingress for the service
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: testing-ingress
  annotations:
    kubernetes.io/ingress.class: "nginx"
    cert-manager.io/cluster-issuer: "letsencrypt-prod"
    nginx.ingress.kubernetes.io/rewrite-target: /$2 # Lets us rewrite example.com/something/hello to example.com/hello
    nginx.ingress.kubernetes.io/proxy-read-timeout: "3600"
    nginx.ingress.kubernetes.io/proxy-send-timeout: "3600"
    nginx.ingress.kubernetes.io/affinity: "cookie"
    nginx.ingress.kubernetes.io/session-cookie-name: "route"
    nginx.ingress.kubernetes.io/session-cookie-hash: "sha1"
    nginx.ingress.kubernetes.io/session-cookie-expires: "172800"
    nginx.ingress.kubernetes.io/session-cookie-max-age: "172800"

spec:
  tls:
  - hosts:
    - api.example.com
    - example.com
    secretName: testing-ingress-tls
  rules:
  - host: api.example.com
    http:
      paths:
      - path: /v0(/|$)(.*)
        backend:
          serviceName: platform-app-service
          servicePort: 80
  - host: example.com
    http:
      paths:
      - path: /
        backend:
          serviceName: frontend-app-service
          servicePort: 80

Looks like a user put a nice write-up for this over on Medium that you may find helpful:

https://medium.com/swlh/how-to-use-web-sockets-socket-io-with-digital-ocean-load-balancers-and-kubernetes-dok8s-with-e4dd5531c67e