You can easily set up Mattermost with a subdomain by using nginx or your proxy of choice, which is only a little extra work, and with LE, can also be easily sec

You can easily set up Mattermost with a subdomain by using nginx or your proxy of choice, which is only a little extra work, and with LE, can also be easily secured. This is what I did for Mattermost at my previous job, and it worked quite well.