Collabora / code on another server

I installed nexcloud on my server managed with Plesk under nexcloud.mydomain.org. I could not install Collabora / code on this same server due to difficulties with Plesk.
So I hired a VPS under Debian 8, next to my server, to install Docker and Collabora Code with a subdomain collabora.mydomain.org.
I installed the SSL key without any problems on the subdomain and it is validated here https://www.ssllabs.com/ssltest/
I see well the container launched when I do docker ps
I set the path with the port in the Collabora settings of Nextcloud, but when I try to open a document, I have this error
GuzzleHttp \ Exception \ ConnectException: cURL error 7: Failed to connect to collabora.mydomain.org port 9980: No route to host

I can however access with a browser at collabora.mydomain.org

So I think the problem is at the level of the Firewall and more precisely at the level of the iptable :slight_smile:-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-N DOCKER
-N DOCKER-ISOLATION
-N DOCKER-USER
-A INPUT -i docker0 -j ACCEPT
-A FORWARD -j DOCKER-USER
-A FORWARD -j DOCKER-ISOLATION
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o eth0 -j ACCEPT
-A FORWARD -i eth0 -o docker0 -j ACCEPT
-A DOCKER -d 172.17.0.2/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 9980 -j ACCEPT
-A DOCKER-ISOLATION -j RETURN
-A DOCKER-USER -j RETURN

Can anyone tell me how to open an access to my nexcloud server?

thank you in advance