Subdomain Mobile Redirect

Hi. I am trying to use the mobile redirect for a subdomain (not the root domain). For instance, I would still like when a user goes to, it takes them to our main landing page. However, I want to make it so when a mobile user goes to, it forwards them to

As of now, I looked around and it seems like I am only able to forward my root domain.

Thanks and please let me know if there is a way to forward my subdomain based on if a mobile user is accessing it.