HAproxy url access only from 192.168.0.0/16

Question

I have

http-request deny if { path -i -m beg /otrs/ } !{ src 192.168.0.0/16 }

This is working fine.

And i'd like to have same possibility whit subdomain, like: ser.example.pl What i mean is subdomain ser, not path. How to achieve that?