How to add port number in “Confirm your email address” link?

Dear GitLab and any developers.

I installed Gitlab CE 12.4.2 to ubuntu 16.04 LTS base.
Then I setup my office SMTP email for sending notification email to user.
SMTP email sending is working normally.

When add new user by admin, GitLab send “Confirmation instructions” email to user.
I have a problem, “Confirm your email address” URL link does not included port number.

For example, my GitLab site URL is “”.
For connecting my GitLab site, URL need to added IP( with PORT_NUMBER(:12345).

< Issue point >
But, now “Confirm your email address” URL link in “Confirmation instructions” email does not contain the port number.
URL link set “…”, so when user click a link, web browser is shown “404 not found” error page.

< Problem >
Due to not including port number in “Confirm your email address” link, when occur “404 not found”,
user should add URL… to… by himself.

< Need to find solution >
I would like to add port number to “Confirm your email address” link as “…”.
Where should I modify gitlab.rb?

Please, help and resolve my issue.

Thank you.