It should, and yes I used to think that. I'm in the UK and some routers just fail to work properly with higher port numbers, especially cheap routers from cheaper providers. Once you start getting above 8000 the traffic is limited thus me saying try a lower port number. Plus yunohost doesn't really ask for a port number as you should add a domain first, then install the application (it uses docker btw) on that domain, then cloudflare to the domain. So the port number isn't required. I'm guessing, but can't be sure, that this is the real issue. yunohost adds a self signed cert and configures the firewall etc. so if you don't do it right using a cloudflare tunnel it just doesn't work. I'm guessing the OP hasn't done it like this, and then it will never work - believe me I've tried. yunohost also adds fail2ban, firewall inside yunohost and various other ways to protect what is served