Cannot access my switch on a second nic

Here is my setup:

ISP provided modem/switch (In bridge mode) ——> Asus Router —-> Desktop PC (with two nics) —–> Cisco Switch

I have IP Cameras attached to the switch, and I do not want the cameras to have internet access (Chinese Cameras)

I am 100% sure that everything is on the same subnet.

Router IP: 192.168.200.20

Switch Ip: 192.168.200.241

Desktop Nic 1: DHCP

Desktop NIC2 (connected to switch) : 192.168.200.250

I cannot access the switch. I am not talking about CLI.
I need to be able to talk to the IP Cam, but I cannot.