Wireguard help...

I feel like this should be so simple and either I am missing a major fundamental piece or this is just bug... I am very much an amateur when it comes to networking but at my house I have multiple networks that are isolated and some with varying levels of restrictions and am able to get everything working perfectly and easily with a firewalla purple... I tried to set one up for my father with only ONE network and wireguard and it is not going as smoothly. He has one PC on ethernet and a wifi router on the same network. We enabled wireguard so he can access his home network when out of town. We can not for the life of us get things to talk to each other. I am not able to even ping something unless I use the new(er) ip address that is associated with wireguard. I can not get the laptop to ping the pc when the laptop is on wireguard. I have added rules to allow for this and what is also strange is next to the rule that counts flows I am not getting any increase in number. I am only able to ping each other if both are on wireguard and I use the ip that wireguard gives it. This mean that all address for file-sharing and what not dont work as wireguard gave it a "new" ip... Please help... I am sure there is more info that is needed so please let me know what else I am missing. Thanks!