Mango VPN Server, Static IP's with no gateway setup

I have an enviroment where I have a LAN network where there are dummy devices with static IPs defined and what I believe have no gateways. I wanted to allow a technician to remote in to configure the devices from a VPN. They are,,

I successfully setup a Wireguard VPN server on the mango (GL-MT300N-V2). If I plug in a windows device into the switch attached to the mango, it will obtain an IP and I can ping it from a client connected to the VPN.

The problem is the static IP devices that I don’t think have default gateways configured. If I plug into the LAN port of the mango, I can ping them, but not from the VPN. They don’t have normal web interfaces I can use to check the settings, you need special software.

To try and work around this I tried changing the LAN network on mango to, and VPN network to but still can’t ping the devices – although I can ping anything else on or even

Am I correct in assuming that to communicate on the VPN, these devices need the gateway of the router defined? Is there any work around?

Can you give a topology?