I was considering self hosting at home. If the local network should be disconnected IMHO only a DMZ will help. My router doesn't support that so the setup will

I was considering self hosting at home. If the local network should be disconnected IMHO only a DMZ will help. My router doesn't support that so the setup will be: ISP router (with disabled wlan) <-> firewall <- home router (with wlan) and the firewall can then separate the network by port. WAN for the firewall is the LAN Port of my ISP router. Is that a good setup?