MinimWatch subnet not found with VPN

[Metalface]

I've been trying to setup a MinimServer but I can't seem to get MinimWatch to detect the server. The server is on a Synology NAS and it is running. I'm connected to the network via a VPN. The NAS's local IP is 192.168.1.38 and I can connect to it via the VPN. I can also access 192.168.1.38:9790. If I don't specify a subnet MinimWatch sets 192.168.1.200 as the active subnet, which is the local IP that the VPN server provides me with, but it won't detect the server. If I specify 192.168.1.0 as the active subnet, MinimWatch tells me it can't find that subnet (and the server is still not found).

I've tried disabling Windows firewall - didn't help.

To me it seems that there's something wrong with my VPN connection. I'm not very familiar with networking but I can follow guides and I'm not afraid to do some research. What could cause this kind of behavior? Unfortunately I can't test the server without the VPN right now.

Oh, and my hardware is: MinimWatch on a Windows laptop, VPN server on an Edgerouter Lite, MinimServer on Synology DS215j which is connected to the Edgerouter via an ethernet cable.