Redirect all subdomains but one with specific port

Hi there.

I'm looking to redirect all subdomains but one with specific 6789 port to be redirected to for the Web Admin. So if I visit I get redirected to

Is there an option to add Rewrite conditions & rules for OpenLiteSpeed Web Admin itself?

I've looked into docs and forums, but there seems to be no intuitive or simple way to do it (without editing admin backend code).
I also tried to:
  1. Add rewrite rules in Virtual Host > Rewrite settings (didn't work)
  2. Add .htaccess in virtual host map (didn't work)
  3. Add .htaccess in /usr/local/lsws/admin/html/ (didn't work)

Thanks in advance for any info provided!