I think a found some lead. Collabora/code docker container is crashing since the STATUS uptime is always less than a second up and then it the up time resets to Up 1 seconds…
sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ff7bb05494f4 collabora/code "/bin/sh -c 'bash ..." 12 hours ago Up 34 seconds 127.0.0.1:9980->9980/tcp peaceful_haibt
5a0be9cc3e04 mquandalle/wekan "/bin/sh -c 'bash ..." 14 months ago Up 2 months 0.0.0.0:8081->80/tcp wekan_wekan_1
02cf142a5f3c mongo "/entrypoint.sh mo..." 14 months ago Up 2 months 27017/tcp wekan_wekandb_1
I’m using Docker version 17.05.0-ce.
In my case I think it’s not related to wrong Nginx configuration, but more about a instable docker image of collabora. If I join the container (docker exec -i -t ff7bb05494f4 /bin/bash). I will get kicked-out after some seconds because it’s crashing 
EDIT:
There is already a topic about my problem, see: