FTP reverse proxying based on hostname/domain
I have 3 servers which all have FTP on the same port. They are all at the same ip address behind the same router. The router cannot port forward based on the domain requested, only the port.
Currently all requests go through the router to server1.
I would like requests to
s1.example.com:21 to go to
s2.example.com:21 to go to
server2:21 and etc.
Is there a simple way to do this with Apache or by some other means?