Simply typing in the IP address of the router does not load the page.
Yup; using WG as you do means your laptop is now on a completely different network.
That’s probably going to have to be an adjustment to the firewall ruleset when WG Server is active. I don’t have the skills for it to be certain of a solution but fortunately @radishman seems quite good at communicating back changes the devs come up with to fixes to bugs like this.