Some doubts about nextcloud+collabora: 2 reverse proxies?

Hello! I’ve unsuccessfully tried to use collabora to integrate with my Nextcloud server and I would like some advices and clarification.

To give you a picture of my scenary: I have a Proxmox server at home running:

  1. a container running nginx reverse proxy
  2. a container running dnsmasq (so I have name resolution on my lan)
  3. another container running Nextcloud server
  4. a qemu vm running debian 9 + docker to run collabora
  5. other containers running diferent services (a wiki, a wordpress test site, and so on).

I’m using NOIP service (my ISP gives me dynamic IP) so I can reach nextcloud using this url (example) https:// mydomain. no-ip. org/nextcloud/ when outside my home. Note it’s already a subdomain and I have no control over it.
or this one: https:// nextcloud. home. lan/nexcloud/ if I’m in my lan.

I’ve tried following the official guide but I’m not able to connect nextcloud with collabora.
I’ve tried launching collabora using “nextcloud. home. lan” and "mydomain. no-ip. org"
Also tried to connect Nextcloud to collabora using “collabora. home. lan” and “mydomain. no-ip. org

These are logs on Nextcloud:

Error	richdocuments	GuzzleHttp\Exception\ConnectException: cURL error 7: Failed to connect to collabora.home.lan port 443: Connection refused	2017-10-20T11:38:03-0300
Error	richdocuments	GuzzleHttp\Exception\ConnectException: cURL error 7: Failed to connect to 192.168.0.16 port 443: Connection refused	2017-10-20T11:37:36-0300
Error	richdocuments	GuzzleHttp\Exception\ServerException: Server error response [url] https://mydomain.no-ip.org/hosting/discovery [status code] 502 [reason phrase] Bad Gateway	2017-10-20T11:29:29-0300
Error	richdocuments	GuzzleHttp\Exception\ConnectException: cURL error 7: Failed to connect to collabora.home.lan port 443: Connection refused	2017-10-20T11:29:02-0300
Error	richdocuments	GuzzleHttp\Exception\ConnectException: cURL error 7: Failed to connect to collabora.home.lan port 9980: Connection refused	2017-10-20T11:26:24-0300
Error	richdocuments	GuzzleHttp\Exception\ConnectException: cURL error 7: Failed to connect to mydomain.no-ip.org port 9980: Connection refused	2017-10-20T11:25:43-0300

I’m not sure if I have to add reverse proxy directives to my existent container (as I’ve tried) or have another reverse proxy just for collabora (inside same VM alongside with docker)

Any advice?
Thank you in advance

(spaces added to URL otherwise I can’t post)