custom mysql DB_PORT is not working. only default 3306 works

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Expected Behavior

Connection to mysql on defined port should work.

Current Behavior

currently only works on default 3306 mysql port

Steps to Reproduce

1. set specific DB_PORT to connect to specific port for mysql.
   Example : DB_PORT: 3310
   :Error: do not connect Please fix it. thanks

Environment

OS:
CPU architecture: x86_64
How docker service was installed:

In case of providing Port at the end of DB_HOST other issue.
Logs: when providing - DB_HOST=10.10.0.5:3310
bookstack | nc: getaddrinfo: Name does not resolve

[github-actions]

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[tobbenb]

You do not supply the info we ask for. Please update your issue with the info we ask for.

@tobbenb I try to explain I think what is necessary.
I am using example docker-compose.yml provided in this repo.
I am just trying to connect to external mysql server with specific port 3310, with DB_PORT: 3310 environment variable.

I think This will be enough to reproduce it.
Please tell me if you need some specific information.
Thanks for reply.