I have passthrough mode set on my modem&router (w/dhc lease fixed on and with port forwarding on towards my gl inet router). In addition, I have wifi on on both the modem/router and on the gl inet router (which is the slate axt-1800).
VPN openvpn and wireguard servers are turned on the slate. Ports open on ATT router are TCP 443/ 943, and UDP 1194/51820,51822.

My devices in the home mostly connect to the modem/router wifi.

Is this dangerous having the wifi on both devices slate and the modem/router combo device from the ISP, with passthrough mode on?
I only did this type of set up to get it to work quickly, so happy to adjust as long as vpn keeps working.

Thanks

Could cause issues and is generally not recommended.

Dangerous? It depends on what "pass-through" means on your device. If it disables NAT and firewalling it might be dangerous, yep.