Thanks for you answer @fbartels ! Unfortunetly Nextcloud and MM do not share the same domain but are on a different sub domains. I found a lot of solutions concerning vhost config for installations running nginx but it’s more difficult to find something up to date for apache. Would you have some advices for such an installation on the parameters I would have to specify in my vhost apache config ?
Concerning point 2- could this be useful ? : https://github.com/mattermost/mattermost-redux
Thanks 