It could possibly be because of several interfaces on your PC which prefer one over another. In this case - WiFi.
Could you please go to your internet adapter settings (WiFi) and set them like this:
Add static IP to your interface and add 192.168.1.1 as your preferred DNS server.
Then go to "Advanced..." settings and change metric to "1".
NOTE: These settings may not work with other wifi access points that have different subnet or infrastructure (DHCP server, static IP leases and so on)..
Also, please make sure you do not have anything enabled like Ping reboot, that could restart your router once your connection to the internet is lost - which would cause you to not reach WebUI because of restarting router process.