Virtual Server & Self IP's on the same IP subnet

That mean you need to write appropriate route. For example:

1. Self IP is 10.10.10.1

    

2. VIP is 10.10.20.1

    

On router you must add route (cisco): ip route 10.10.20.1 255.255.255.255 10.10.10.1 it's mean that your VIP is behind Self IP.

For communicating 2 different subnets there must be Layer-3 device in front of your F5 device.