ESXi 6.5 was installed on the virtual server.
May I assume that the "virtual server" you are talking about is an ESXi host?
Are you able to ping the ESXi virtual machine by its IP address?
How exactly does your network setup look like?
Yes. The host of the virtual server is ESXi.
The version of ESXi was 6.0.
On the ESXi host side, we conducted the Testing Management Network. The result is ping OK for both local IP and external IP.
The network adapter uses VMXNET３.
For network setting, IPv4, Net Mask, Gate way, DNS has already been assigned.
I'm not quite sure whether I understand your setup, and what exactly you want to achieve.
A picture (even hand-drawn) with the host names, network configuration/settings, ... might help.