When configuring a two-armed Virtual Service, routing issues can occur. A two-arm configuration is a Virtual Service in which the Virtual Service address is in a separate subnet to the servers. A common fix to this issue is to enable Subnet Originating Requests. Instead of the server responding to a request from the Virtual Service IP address, the server will see the LoadMaster's local interface address which it can readily respond to, without worrying about default gateways or static routes.
This Subnet Originating Requests option can be enabled or disabled in the LoadMaster Web User Interface (WUI) by going to System Configuration > Miscellaneous Options > Network Options and ticking or unticking the relevant check box.