I have an OnlyOffice Document Server running on my server bound to port 8888 via Docker. Now I want to use a Let's Encrypt certificate to ensure a safe connection (self signed certificates won't work). I use the following config in Apache to rewrite office.example.org to office.example.org:8888 but it throws me an error 500
<VirtualHost *:443>
ServerName office.example.org
ProxyPreserveHost On
ProxyPass / https://localhost:8888/
ProxyPassReverse / https://localhost:8888/
</VirtualHost>
All necessary modules are enabled. Has anyone any idea on how to solve this problem or a different idea to solve the Let's Encrypt problem?