Just some thoughts, things to check and questions to help narrow this down.
1- Is the switch IP also on the same 10.51.1.# network?
2 - If it isn't, do the virtual servers have the proper default gateway configured?
3 - If it is, can other devices on the same network ping the virtual servers?
4 - Can the virtual servers reach (or ping) devices on and off the local subnet?
5 - Is port for the virtual server configured as an access port or a trunk port?
6 - If it is configured as a trunk port, are the virtual servers in the proper VLAN?
7 - Can you provide a switch config?
Regards
Regards