Accessing network devices behind ICS from main network

Question

I have a bunch of devices sitting behind a Windows internet connection sharing network that I want to access from my main network. The network is set up like the following:

   Gateway (192.168.1.1)
     /                  \
    /                 wireless devices/pihole (192.168.1.*)
   /
Desktop wlan0 (192.168.1.2)
Desktop ICS via eth0 (192.167.137.1)
            |
   Switch (192.168.137.10)
        /         \
 PS4 (DHCP)     Shield TV (192.168.137.2) 

I want to access the switch/ps4/Shield TV using a wireless device connected to the gateway but it doesn't seem to work. I have configured a static route on the gateway to redirect 192.168.137.0/24 to 192.168.1.2 but the packets are being dropped at the Desktop.

I've tried a few things to fix it. I set the "unidentified network" that windows detects on eth0 to private, as well as disabling windows firewall and manually setting a route in windows to 192.168.137.0/24 via 192.168.137.1.

None of these have worked and any packets sent to 192.168.137.x from the gateway get dropped at 192.168.1.2. Is this a limitation of ICS or am I missing something?