Subdomain not working when network is installed on sub directory

I’ve a network installed on my domain. I’m actually using subdomain for mobile version. Suppose i’ve a set dev1.pw when you will open it in the mobile, it will redirect to mob.dev1.pw and will open mobile version. Now when i have installed multi network and i have choosen subdirectory for other sites, in this case i’m not been able to access subdomain.
Any ideas how i can do this ???